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Journal articles on the topic 'Ionisation'

Author: Grafiati

Published: 4 June 2021

Last updated: 29 March 2025

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1

Ford, M. J. "Studies of the Electron-impact Double-ionisation Process in Magnesium using Coincidence Techniques." Australian Journal of Physics 51, no. 4 (1998): 665. http://dx.doi.org/10.1071/p98013.

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This article will review recent measurements of the electron-impact double-ionisation of atomic magnesium. Results for the resonant Auger double-ionisation process with coincident detection of all three outgoing electrons, the (e, 3e) experiment, and for the direct double-ionisation process where only two outgoing electrons are detected, the (e, (3 – 1)e) experiment, will be discussed. The results are analysed with reference to ionisation mechanisms and comparisons are made with calculated double-ionisation cross sections.

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2

Ong, Duu Sheng, Ai Hui Tan, Kan Yeep Choo, Keat Hoe Yeoh, and John P. R. David. "Weibull-Fréchet random path length model for avalanche gain and noise in photodiodes." Journal of Physics D: Applied Physics 55, no. 6 (November 2, 2021): 065105. http://dx.doi.org/10.1088/1361-6463/ac31f0.

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Abstract A four-parameter Weibull-Fréchet (WF) distribution function has been introduced in the random path length (RPL) model for nonlocal modelling of soft-threshold ionisation in semiconductors. The WF function has been demonstrated to be capable of reproducing the realistic probability distribution function (PDF) of electron and hole ionisation path lengths extracted from full band Monte Carlo (FBMC) transport simulations of bulk GaAs. The electron-initiated multiplication in GaAs avalanche photodiodes (APDs) calculated by the WF-RPL model is in excellent agreement with the results from FBMC. The predicted excess noise factor is closer to that of FBMC as compared to the hard threshold RPL model. The advantage of this improved RPL model as a tool for predicting the PDF of electron and hole ionisation path lengths in AlAs0.56Sb0.44 from the experimentally measured avalanche gain and noise has been analysed. The electron ionisation path length PDF of AlAs0.56Sb0.44 has a unique feature of two decay rates with a narrow full width at half maximum and a long tail. The extremely low hole ionisation coefficient in AlAs0.56Sb0.44 is found with a PDF of ionisation path length spanning over 50 µm at an electric field of 600 kVcm−1, supporting the very low hole feedback ionisation in AlAs0.56Sb0.44 APDs. The combination of the detailed and peaked electron’s ionisation path length PDF and of the broad hole’s ionisation path length PDF is responsible for the extremely low avalanche noise in the 1.55 µm thick AlAs0.56Sb0.44 APDs.

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3

REED, VALERIE C. "SUPERINTENSE FIELD IONISATION SUPPRESSION IN THE HIGH FREQUENCY REGIME." Modern Physics Letters B 06, no. 12 (May 20, 1992): 683–701. http://dx.doi.org/10.1142/s0217984992000776.

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We present a brief review of the subject of ionisation suppression, or atomic stabilisation, in intense laser fields. As a preliminary, we outline the general non-linear response of an atom to a strong laser field, describing multiphoton ionisation and harmonic generation. We then discuss methods of suppressing the ionisation rate from an atom, considering two broad regimes: strong field ionisation (I < 1016 W/cm 2), in which the suppression mechanism in generally interpreted in terms of quantum interference; and superintense field ionisation (I > 1016 W/cm 2), in which the Kramers-Henneberger frame is used to interpret why atomic stabilisation can occur.

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4

McKoy, V., SN Dixit, RL Dubs, and DL Lynch. "Dynamics of Single and Multi-photon Ionisation Processes in Molecules." Australian Journal of Physics 39, no. 5 (1986): 761. http://dx.doi.org/10.1071/ph860761.

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Single-photon ionisation and resonant multiphoton ionisation studies, which can now be carried out using synchrotron radiation and pulsed dye lasers respectively, are providing important dynamical information on molecular photoionisation. In this paper we discuss some results of our recent studies of several, single- and multi-photon ionisation processes in molecules. The results will be taken from our studies of (i) single-photon ionisation of linear molecules with emphasis on the role of shape and autoionising resonances on these cross� sections, (ii) photoionisation from oriented NiCO as a simple but realistic model of photoemission in adsorbate-substrate systems, and (iii) resonant multiphoton ionisation of H2.

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5

Padma, R., and PC Deshmukh. "Near-threshold Behaviour of Generalised Oscillator Strengths for 2p Ionisation." Australian Journal of Physics 47, no. 3 (1994): 271. http://dx.doi.org/10.1071/ph940271.

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Near the ionisation threshold, the behaviour of the generalised oscillator strength (GOS) is sensitive to the choice of the model atomic potential. In electron-impact ionisation, 'delayed maxima' of the GOS often occur near the ionisation threshold due to centrifugal barrier effects. In the present work, the sensitivity of this important effect of the centrifugal barrier to the model atomic potential has been studied using two local density atomic potentials, namely, the nonrelativistic Hartree-Slater potential and the relativistic RCB potential. Calculations have been done for electron-impact 2p ionisation of atomic oxygen, neon, aluminium, argon, iron and zinc. The GOS results for 2p ionisation of oxygen and aluminium are presented to illustrate the results.

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6

Ernest, A., SC Haydon, and MT Elford. "Excited-state Quenching Phenomena in Weakly Ionised Nitrogen." Australian Journal of Physics 39, no. 4 (1986): 479. http://dx.doi.org/10.1071/ph860479.

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A number of studies of the ionisation behaviour of molecular nitrogen have revealed the importance of N 2(A 3L ;;) metastable particles which are created by direct electron impact excitation or cascade processes. More recent studies using cleaner gas samples have indicated that the ionisation current may be affected by the presence of a second metastable particle. The possible identity of this second metastable particle and the sensitivity of the ionisation current to its presence have been investigated by observing the changes in the pre-breakdown ionisation current as a function of the purity of the N 2 gas samples. Both the spatial and temporal behaviour of the ionisation current were observed. Particular care was required in this study to ensure that stable electrode surface conditions were obtained and the procedures adopted are described in detail. The addition of CO and H2 to the N 2 samples at the parts per million level confirmed the dominant quenching action of CO. Further consideration of the spatial growth of ionisation has demonstrated that an ionisation mechanism involving both N2(A 3L ;;) and N2(a' 1 L;;-) particles provides a plausible explanation for the observations and should be further investigated.

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7

Prashant, Abhishek, Meetu Luthra, Kanupriya Goswami, Anand Bharadvaja, and Kasturi Lal Baluja. "Positron Scattering from Pyrimidine." Atoms 11, no. 3 (March 10, 2023): 55. http://dx.doi.org/10.3390/atoms11030055.

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The positron impact cross-sections of pyrimidine molecules are reported from 1 eV to 5000 eV. These cross-sections include differential elastic, integral elastic, and direct ionisation. The elastic cross-sections are computed using the single-centre expansion scheme whereas the direct ionisation cross-sections are obtained using the binary-encounter-Bethe formula. The integral and differential cross-sections exhibit consistency with the experimental and other theoretical results. The direct ionisation cross-sections, which are reported for the first time, are compared with the experimental inelastic cross-sections (the sum of excitation and ionisation) to assess the trends in theoretically computed ionisation cross-sections and with the corresponding results for the electrons. The incoherently summed elastic and ionisation cross-sections match very well with the total cross-sections after 40 eV indicating the minimal impact of the positronium formation and electronic excitation processes. Based on this study, we recommend that the experimental data of the inelastic cross-sections reported by Palihawadana et al. be revisited.

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8

Gates, Paul J. "Atmospheric pressure chemical ionisation mass spectrometry for the routine analysis of low molecular weight analytes." European Journal of Mass Spectrometry 27, no. 1 (February 2021): 13–28. http://dx.doi.org/10.1177/14690667211005055.

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The routine analysis of low molecular weight analytes by mass spectrometry is often complicated by the lability of the analyte’s functional groups and/or the lack of moieties that can be easily charged. If a molecule is too labile this precludes analysis by techniques such as electron ionisation or chemical ionisation as the analyte will undergo thermal decomposition prior to ionisation as well as spontaneous fragmentation during the ionisation process. If the analyte has a low propensity to form ions in electrospray ionisation (i.e., lacks acidic or basic sites) then often no analyte related ions are observed. In this paper, the robustness and versatility of the established method of atmospheric pressure chemical ionisation is demonstrated for the analysis of low molecular weight analytes. The utility of the technique is demonstrated through the analysis of 30 reference standards of varying functionality, and further by the analysis of 75 synthetic samples which were problematic when analysed by electron or electrospray ionisation. The resulting spectra are dominated by intact molecular species ([M+H]+ and M+ in positive ion mode and [M − H]− and [M + Cl]− in negative ion mode) along with logical neutral losses reminiscent of what you might expect from the analyte’s structure (losses of H2O from alcohols or CO from aldehydes etc). This paper presents atmospheric pressure chemical ionisation as an essential tool for broadening the chemical space of successful analyses for any routine mass spectrometry service laboratory of facility.

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9

Pagano, P., A. Bemporad, and D. H. Mackay. "Hydrogen non-equilibrium ionisation effects in coronal mass ejections." Astronomy & Astrophysics 637 (May 2020): A49. http://dx.doi.org/10.1051/0004-6361/202037638.

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Context. A new generation of coronagraphs used to study solar wind and coronal mass ejections (CMEs) are being developed and launched. These coronagraphs will heavily rely on multi-channel observations where visible light (VL) and UV-EUV (ultraviolet-extreme ultraviolet) observations provide new plasma diagnostics. One of these instruments, Metis on board ESA-Solar Orbiter, will simultaneously observe VL and the UV Lyman-α line. The number of neutral hydrogen atoms (a small fraction of coronal protons) is a key parameter for deriving plasma properties, such as the temperature from the observed Lyman-α line intensity. However, these measurements are significantly affected if non-equilibrium ionisation effects occur, which can be relevant during CMEs. Aims. The aim of this work is to determine if non-equilibrium ionisation effects are relevant in CMEs and, in particular, when and in which regions of the CME plasma ionisation equilibrium can be assumed for data analysis. Methods. We used a magneto-hydrodynamic (MHD) simulation of a magnetic flux rope ejection to generate a CME. From this, we then reconstructed the ionisation state of hydrogen atoms in the CME by evaluating both the advection of neutral and ionised hydrogen atoms and the ionisation and recombination rates in the MHD simulation. Results. We find that the equilibrium ionisation assumption mostly holds in the core of the CME, which is represented by a magnetic flux rope. In contrast, non-equilibrium ionisation effects are significant at the CME front, where we find about 100 times more neutral hydrogen atoms than prescribed by ionisation equilibrium conditions. We find this to be the case even if this neutral hydrogen excess might be difficult to identify due to projection effects. Conclusions. This work provides key information for the development of a new generation of diagnostic techniques that aim to combine visible light and Lyman-α line emissions. The results show that non-equilibrium ionisation effects need to be considered when we analyse CME fronts. Incorrectly assuming equilibrium ionisation in these regions would lead to a systematic underestimate of plasma temperatures.

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10

Lohmann, Birgit, S. J. Cavanagh, M. A. Haynes, I. Taouil, A. Duguet, and A. Lahmam-Bennani. "Investigating Inner Shell Ionisation via the (e, 2e) Technique." Australian Journal of Physics 51, no. 4 (1998): 679. http://dx.doi.org/10.1071/p97093.

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The (e, 2e) technique has been applied successfully to valence shell ionisation of many targets, but studies of inner shell ionisation by this technique have been limited. The triple differential cross section for the latter process exhibits behaviour which is very different to that observed for valence shell ionisation, particularly when the energy of the slow ejected electron is decreased below the binding energy of the inner shell orbital. Our recent results for inner shell ionisation of argon and krypton will be discussed, and comparisons made with distorted wave calculations.

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11

He, Xu-Cheng, Jiali Shen, Siddharth Iyer, Paxton Juuti, Jiangyi Zhang, Mrisha Koirala, Mikko M. Kytökari, et al. "Characterisation of gaseous iodine species detection using the multi-scheme chemical ionisation inlet 2 with bromide and nitrate chemical ionisation methods." Atmospheric Measurement Techniques 16, no. 19 (October 9, 2023): 4461–87. http://dx.doi.org/10.5194/amt-16-4461-2023.

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Abstract. The multi-scheme chemical ionisation inlet 1 (MION1) enables rapid switching between the measurement of atmospheric ions without chemical ionisation and neutral molecules using various atmospheric pressure chemical ionisation methods. In this study, we introduce the upgraded version, the multi-scheme chemical ionisation inlet 2 (MION2). The new design incorporates enhanced ion optics, resulting in increased reagent ion concentration, ensuring a robust operation, and enabling the use of multiple chemical ionisation methods with the same ionisation time. In order to simplify the regular calibration of MION2, we developed an open-source flow reactor chemistry model called MARFORCE. This model enables quantification of the chemical production of sulfuric acid (H2SO4), hypoiodous acid (HOI), and hydroperoxyl radical (HO2). MARFORCE simulates the convection–diffusion–reaction processes occurring within typical cylindrical flow reactors with uniform inner diameters. The model also includes options to simulate chemical processes in the following two scenarios: (1) when two flow reactors with different inner diameters are connected and (2) when two flows are merged into one using a Y-shaped tee, although with reduced accuracy. Furthermore, the chemical mechanism files in the model are compatible with the widely used Master Chemical Mechanism (MCM), allowing for future adaptation to simulate other chemical processes in flow reactors. Furthermore, we conducted a comprehensive characterisation of the bromide (Br−) and nitrate (NO3-) chemical ionisation methods with different ionisation times. We performed calibration experiments for H2SO4, HOI, and HO2 by combining gas kinetic experiments with the MARFORCE model. The evaluation of sulfur dioxide (SO2), water (H2O), and molecular iodine (I2) involved dilution experiments from a gas cylinder (SO2), dew point mirror measurements (H2O), and a derivatisation approach combined with a high-performance liquid chromatography quantification (I2), respectively. Our findings indicate that the detection limit is inversely correlated with the fragmentation enthalpy of the analyte–reagent ion (Br−) cluster. In other words, stronger binding (resulting in a larger fragmentation enthalpy) leads to a lower detection limit. Additionally, a moderately longer ionisation time enhances the detection sensitivity, thereby reducing the detection limit. For instance, when using the Br− chemical ionisation method with a 300 ms ionisation time, the estimated detection limit for H2SO4 is 2.9×104 molec. cm−3. Notably, this detection limit is even superior to that achieved by the widely used Eisele-type chemical ionisation inlet (7.6×104 molec. cm−3), as revealed by direct comparisons. While the NO3- chemical ionisation method remains stable in the presence of high humidity, we have observed that the Br− chemical ionisation method (Br−–MION2) is significantly affected by the air water content. Higher levels of air water lead to reduced sensitivity for HO2 and SO2 under the examined conditions. However, we have found that a sharp decline in sensitivity for H2SO4, HOI, and I2 occurs only when the dew point exceeds 0.5–10.5 ∘C (equivalent to 20 %–40 % RH; calculated at 25 ∘C throughout this paper). For future studies utilising the atmospheric pressure Br− chemical ionisation method, including Br−–MION2, it is crucial to carefully consider the molecular-level effects of humidity. By combining approaches such as the water-insensitive NO3-–MION2 with Br−–MION2, MION2 can offer more comprehensive insights into atmospheric composition than what can be achieved by either method alone. By employing instrument voltage scanning, chemical kinetic experiments, and quantum chemical calculations, we have conclusively established that the presence of iodine oxides does not interfere with the detection of HIO3. Our comprehensive analysis reveals that the ions IO3-, HIO3⚫NO3-, and HIO3⚫Br−, which are detected using the Br− and NO3- chemical ionisation methods, are primarily, if not exclusively, generated from gaseous HIO3 molecules within atmospherically relevant conditions.

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12

Crothers, D. S. F. "Quantal threshold ionisation." Journal of Physics B: Atomic and Molecular Physics 19, no. 4 (February 28, 1986): 463–83. http://dx.doi.org/10.1088/0022-3700/19/4/013.

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13

Eberly, J. H., and J. Javanainen. "Above-threshold ionisation." European Journal of Physics 9, no. 4 (October 1, 1988): 265–75. http://dx.doi.org/10.1088/0143-0807/9/4/004.

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14

Rosset, Roland. "Ionisation des aliments." Bulletin de l'Académie Nationale de Médecine 186, no. 4 (April 2002): 805–17. http://dx.doi.org/10.1016/s0001-4079(19)34300-6.

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15

Nicholson, K. "Ionisation gauge refurbishment." Vacuum 38, no. 8-10 (January 1988): 962. http://dx.doi.org/10.1016/0042-207x(88)90547-7.

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16

Maslen, E. N., and B. E. Etschmann. "Bonding without ionisation." Australian Journal of Physics 53, no. 2 (2000): 299. http://dx.doi.org/10.1071/ph99027.

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Charges are calculated for diatomic molecules by partitioning the promolecular density with projection operators derived from free atom potentials. The promolecular charges thus obtained have physically reasonable magnitudes, which are moderately sensitive to interatomic distances and thus to bond type. Their signs are negative for cations and positive for anions. Trends in these charges correlate with subshell structure. Due to the long range of their electrostatic potentials, the cations compete successfully for electrons at the expense of the anions in the density partitioning. This implies that the cation states become overfilled when the atoms overlap, favouring a flow of electrons away from the cation towards the vacant anion states. That accounts for the positive cations and negative anions observed when molecular densities are partitioned with projection operators based on free atom electron densities.

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17

Maier, J. P. "Electron impact ionisation." Journal of Electron Spectroscopy and Related Phenomena 36, no. 3 (January 1985): 305. http://dx.doi.org/10.1016/0368-2048(85)80027-x.

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18

Altmann, Korinna, Rolf-Dieter Schulze, Gundula Hidde, and Jörg Friedrich. "Elektrospray-Ionisation (ESI)." Vakuum in Forschung und Praxis 23, no. 6 (December 2011): 17–23. http://dx.doi.org/10.1002/vipr.201100471.

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19

Agostini, P., and G. Petite. "Double multiphoton ionisation via above-threshold ionisation in strontium atoms." Journal of Physics B: Atomic and Molecular Physics 18, no. 10 (May 28, 1985): L281—L286. http://dx.doi.org/10.1088/0022-3700/18/10/004.

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20

Mingozzi, M., F. Belfiore, G. Cresci, K. Bundy, M. Bershady, D. Bizyaev, G. Blanc, et al. "SDSS IV MaNGA: Metallicity and ionisation parameter in local star-forming galaxies from Bayesian fitting to photoionisation models." Astronomy & Astrophysics 636 (April 2020): A42. http://dx.doi.org/10.1051/0004-6361/201937203.

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We measured gas-phase metallicity, ionisation parameter, and dust extinction for a representative sample of 1795 local star-forming galaxies using integral field spectroscopy from the SDSS-IV MaNGA survey. We self-consistently derive these quantities by comparing observed line fluxes with photoionisation models using a Bayesian framework. We also present the first comprehensive study of the [S III]λλ9069,9532 nebular lines, which have long been predicted to be ideal tracers of the ionisation parameter. However, we find that current photoionisation model predictions substantially over-predict the intensity of the [S III] lines, while broadly reproducing other observed optical line ratios. We discuss how to nonetheless make use of the information provided by the [S III] lines by setting a prior on the ionisation parameter. Following this approach, we derive spatially resolved maps and radial profiles of metallicity and ionisation parameter. The metallicity radial profiles derived are comparable with previous works, with metallicity declining toward the outer parts and showing a flattening in the central regions. This is in agreement with infall models of galaxy formation, which predict that spiral discs build up through accretion of material, leading to an inside-out growth. On the other hand, ionisation parameter radial profiles are flat for low-mass galaxies, while their slope becomes positive as galaxy mass increases. However, the ionisation parameter maps we obtain are clumpy, especially for low-mass galaxies. The ionisation parameter is tightly correlated with the equivalent width of Hα [EW(Hα)], following a nearly universal relation, which we attribute to the change of the spectral shape of ionising sources due to ageing of H II regions. We derive a positive correlation between ionisation parameter and metallicity at fixed EW(Hα), in disagreement with previous theoretical work that predict an anti-correlation.

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21

Unnikrishnan, K. "Renormalised Perturbation Theory of Resonant Multiphoton Ionisation." Australian Journal of Physics 48, no. 5 (1995): 835. http://dx.doi.org/10.1071/ph950835.

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Perturbation theory of multiphoton ionisation due to a classical electromagnetic field is modified to allow for intermediate resonances with bound states. Complex energies, generally associated with resonances, do not enter into this formalism. For a monochromatic field of frequency u, a constant ionisation rate can then be defined unambiguously and only such continuum states are excited which correspond to the absorption of energy in integral multiples of hu. As an application, differential and total cross sections for the two-photon ionisation of hydrogen, for frequencies below the n = 3 resonance region, are obtained in closed form. Existing data for generalised cross sections, calculated numerically using the complex coordinate method, are in good agreement with the present results. Finally, the mean fractional ionisation resulting from a pulse of finite duration is estimated on the basis of the associated power spectrum. For short pulses, the time dependence of ionisation exhibits a departure from that expected of a time-independent rate.

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22

Munro, Angus I. S., and Larry K. Forbes. "Including ionisation in a simple model of single-bubble sonoluminescence." ANZIAM Journal 47, no. 3 (January 2006): 333–58. http://dx.doi.org/10.1017/s1446181100009871.

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AbstractA small gas bubble in a liquid, when driven by intense ultrasound, collapses and emits light in a process called Single-Bubble Sonoluminescence (SBSL). While the dynamics of driven bubbles are well studied, less is known of the physical conditions in the gas or whether it is necessary to include ionisation in simpler studies of bubble dynamics. In this study, a model was derived from Rayleigh-Plesset dynamics, a van der Waals equation of state and the first law of thermodynamics (including interfacial heat transfer and ionisation). Stronger model ionisation reduced the maximum collapse temperature, and altered other collapse characteristics. Chaotic parameter regions are proximal to, but not coincident with, known stable SL regions. Resonant behaviour was only markedly affected by ionisation close to these chaotic regions.

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23

Lu, I.-Chung. "Development of a Next-Generation Ionisation Technique in Mass Spectrometry." Impact 2022, no. 1 (February 4, 2022): 59–61. http://dx.doi.org/10.21820/23987073.2022.1.59.

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Mass spectrometry (MS) has a wide range of applications. Assistant Professor I-Chung Lu, Department of Chemistry, National Chung Hsing University, Taiwan, is working to improve and better understand aspects of MS in order to further broaden its possible applications. A particular focus for Lu and his team is on developing novel techniques or improving conventional ionisation methods to overcome application difficulties in MS, specifically in the detection of labile and unstable species. Those techniques extend the MS as a powerful tool to study critical reaction intermidiates and mechanisms. A novel ionisation technique called matrix-assisted ionisation (MAI) is another research focus for Lu and is something that he wants to shed greater light on due to its unclear ionisation process and potential for MS. Lu is seeking to enhance fundamental knowledge of spontaneously charge separation by studying ionisation processes in MAI. Lu and the team have combined a portable spectrometer and dedicated MAI source that has proven to directly detect drugs in urine and blood plasma rapidly. This fast-screen platform also has potential application to the diagnosis and clinical fields.

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24

Stehmann, A., R. J. W. Meesters, and Horst Fr Schröder. "Mass spectrometric analytical methods for the determination of endocrine disrupting chemicals (EDCs)." Water Science and Technology 50, no. 5 (September 1, 2004): 165–71. http://dx.doi.org/10.2166/wst.2004.0324.

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This paper describes a method for the determination of endocrine disrupting chemicals (EDCs) in waste water. The method involves a SPE-C18 extraction followed by a SPE-silica gel column clean up and elution of the analytes with a mixture of acetone/pentane (2+1). Thereafter derivatisation of the analytes with heptafluorobutyric acid anhydride (HFBA) and analysis by gas chromatography/mass spectrometry (GC/MS) with positive electron impact ionisation (EI) or negative chemical ionisation (NCI) using methane as reactant gas was performed. The two different ionisation techniques were compared and the negative chemical ionisation technique proved significant lower limits of detection (LODs) and quantitation (LOQs) than positive electron impact ionisation. Recoveries of the analytes in various spiked waste water samples ranged from 75.4 to 96.9%. The concentrations of the EDCs in feed waste water from three different waste water treatment plants (WWTPs) ranged from non-detectable up to a concentration of 10,305 ng/L for 4-NP and in the corresponding effluent samples from non-detectable to 723 ng/L for BPA.

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25

Coplan, MA, JP Doering, DH Madison, JH Moore, and AA Pinkás. "Electronic Structure Information from Electron Impact Ionisation Experiments." Australian Journal of Physics 49, no. 2 (1996): 321. http://dx.doi.org/10.1071/ph960321.

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Electron impact ionisation with full determination of the kinematics (measurement of energies and momenta of the incident, scattered and ejected electrons) has proven to be useful for investigating both the electronic structure of atoms and molecules and the mechanism of ionisation. These experiments are, by definition, coincidence experiments since it is necessary to be sure that all the detected electrons originate from the same collision. For single-electron ionisation, (e, 2e), the emphasis has been on momentum densities and spectroscopic factors–see for example Coplan et al. (1994), McCarthy and Weigold (1976, 1988, 1991) and Leung (1991). For double ionisation, (e,3e), data are just beginning to emerge, with early results on the Auger process and direct double ionisation (Duguet and Lahmam-Bennani 1992). Both (e, 2e) and (e, 3e) experiments are technically challenging because the signals are small and there is usually a large background. In the last few years, electrostatic spectrographs and position sensitive detectors have improved the resolution and precision of (e, 2e) measurements and have made (e,3e) measurements a practical reality.

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26

Ostrovsky, V. N., and D. A. Telnov. "Adiabatic theory of multiphoton ionisation. I. Ionisation of an isolated level." Journal of Physics B: Atomic and Molecular Physics 20, no. 11 (June 14, 1987): 2397–419. http://dx.doi.org/10.1088/0022-3700/20/11/011.

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27

Bouamra, K., J. R. Vacher, F. Jorand, N. Simiand, and S. Pasquiers. "Electron impact ionisation and partial ionisation cross-sections of iso-octane." Chemical Physics Letters 373, no. 3-4 (May 2003): 237–44. http://dx.doi.org/10.1016/s0009-2614(03)00547-5.

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28

Mokhtari, Mehrdad, Zulkurnain Abdul-Malek, and Gevork B. Gharehpetian. "A critical review on soil ionisation modelling for grounding electrodes." Archives of Electrical Engineering 65, no. 3 (September 1, 2016): 449–61. http://dx.doi.org/10.1515/aee-2016-0033.

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Abstract Grounding electrode resistance non-linearly changes under impulse conditions due to soil ionisation phenomenon. Several models have been proposed to model soil ionisation for grounding electrodes applications. However, to date, there is yet an attempt made to compile all these works into a comprehensive review article. Therefore, this paper is written with the objective of summarizing all related works in this field as a one- stop reference. With reference to the literature, this paper is written to summarize the working principles of the soil ionisation models as well as the accuracy and performance analysis of the models. This paper, particularly highlights the deficiencies of the available models in terms of accuracy and performance. This knowledge will contribute to the development of a new accurate and efficient soil ionisation model.

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29

Houdayer, Pierre S., Daniel R. Reese, Marie-Jo Goupil, and Yveline Lebreton. "Properties of the ionisation glitch." Astronomy & Astrophysics 655 (November 2021): A85. http://dx.doi.org/10.1051/0004-6361/202141711.

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Context. Determining the properties of solar-like oscillating stars can be subject to many biases. A particularly important example is the helium-mass degeneracy, where the uncertainties regarding the internal physics can cause a poor determination of both the mass and surface helium content. Accordingly, an independent helium estimate is needed to overcome this degeneracy. A promising way to obtain such an estimate is to exploit the so-called ionisation glitch, that is, the deviation from the asymptotic oscillation frequency pattern caused by the rapid structural variation in the He ionisation zones. Aims. Although it is progressively becoming more sophisticated, the glitch-based approach faces problems inherent to its current modelling such as the need for calibration using realistic stellar models. This requires a physical model of the ionisation region that explicitly involves the parameters of interest, such as the surface helium abundance, Ys. Methods. Through a thermodynamic treatment of the ionisation region, an analytical approximation for the first adiabatic exponent Γ1 is presented. Results. The induced stellar structure is found to depend on only three parameters, including the surface helium abundance Ys and the electron degeneracy ψCZ in the convective region. The model thus defined allows a wide variety of structures to be described, and it is in particular able to approximate a realistic model in the ionisation region. The modelling work we conducted enables us to study the structural perturbations causing the glitch. More elaborate forms of perturbations than those that are usually assumed are found. It is also suggested that there might be a stronger dependence of the structure on the electron degeneracy in the convection zone and on the position of the ionisation region rather than on the amount of helium itself. Conclusions. When analysing the ionisation glitch signature, we emphasise the importance of having a relation that can take these additional dependences into account.

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30

Donnelly, IJ, and EK Rose. "Ion Densities in Low Temperature Nitrogen Plasmas." Australian Journal of Physics 43, no. 1 (1990): 45. http://dx.doi.org/10.1071/ph900045.

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A cross-section library for the electron ionisation of hydrogen and nitrogen molecules, atoms and ions has been assembled and used for the derivation of reaction rate coefficients assuming a Maxwellian distribution of electron energies. For fixed electron temperatures, the steady-state and time-dependent ionisation of nitrogen molecules have been calculated for conditions relevant to glow discharge plasmas in which the dominant recombination mechanism occurs via the plasma-wall interaction. The analysis shows that there is a threshold electron temperature below which there is no steady-state ionisation. For a small range of temperatures above this threshold there are two possible ionisation states, but at higher temperatures only the more highly ionised state persists. The dependence of the ratio of N+ to N~ ions on filling pressure, confinement time and electron density is also discussed.

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31

Kaur, Jaspreet, Rahla Naghma, and Bobby Antony. "Electron induced ionisation of C3 to C6 ethanoates." RSC Advances 5, no. 26 (2015): 20090–97. http://dx.doi.org/10.1039/c4ra17134a.

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The present article reports the calculation of electron impact total ionisation cross sections for C₃ to C₆ ethanoates for the energy range from the ionisation threshold of the target to 5000 eV.

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32

Harrich, M., M. Friedrich, S. R. Marple, and K. M. Torkar. "The background absorption at high latitudes." Advances in Radio Science 1 (May 5, 2003): 325–27. http://dx.doi.org/10.5194/ars-1-325-2003.

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Abstract. The high latitude ionosphere is more often disturbed than quiet, i.e. fluxes of charged particles dominate over solar controlled ionisation. Nonetheless, the actual amount of the predictable, solar-controlled ionisation and the resulting absorption is of interest for some applications.

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33

Zagorodskikh, S., M. Vapa, O. Vahtras, V. Zhaunerchyk, M. Mucke, J. H. D. Eland, R. J. Squibb, et al. "An experimental and theoretical study of core–valence double ionisation of acetaldehyde (ethanal)." Physical Chemistry Chemical Physics 18, no. 4 (2016): 2535–47. http://dx.doi.org/10.1039/c5cp05758b.

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Core–valence double ionisation spectra of acetaldehyde (ethanal) are presented at photon energies above the carbon and oxygen 1s ionisation edges, measured by a versatile multi-electron coincidence spectroscopy technique and analyzed by means of quantum chemical calculations of transition energies.

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34

Tavard, C. "Double-Ionisation Processes and Electronic Structures." Zeitschrift für Naturforschung A 48, no. 1-2 (February 1, 1993): 251–54. http://dx.doi.org/10.1515/zna-1993-1-246.

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Abstract The electron momentum distribution of a given target can be extracted, under impulsive conditions, from the simple ionisation processes relevant to Compton collisions. This document classifies and investigates the physical mechanisms of double ionisation, in connection with the target electronic structure.

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35

Dujko, S., J. Atić, D. Bošnjaković, R. D. White, P. Stokes, K. R. Hamilton, O. Zatsarinny, et al. "Transport of electrons and propagation of the negative ionisation fronts in indium vapour." Plasma Sources Science and Technology 30, no. 11 (November 1, 2021): 115019. http://dx.doi.org/10.1088/1361-6595/ac3343.

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Abstract We study the transport of electrons and propagation of the negative ionisation fronts in indium vapour. Electron swarm transport properties are calculated using a Monte Carlo simulation technique over a wide range of reduced electric fields E/N (where E is the electric field and N is the gas number density) and indium vapour temperatures in hydrodynamic conditions, and under non-hydrodynamic conditions in an idealised steady-state Townsend (SST) setup. As many indium atoms are in the first ( 5 s 2 5 p ) 2 P 3 / 2 metastable state at vapour temperatures of a few thousand Kelvin, the initial Monte Carlo code was extended and generalized to consider the spatial relaxation and the transport of electrons in an idealised SST experiment, in the presence of thermal motion of the host-gas atoms and superelastic collisions. We observe a significant sensitivity of the spatial relaxation of the electrons on the indium vapour temperature and the initial conditions used to release electrons from the cathode into the space between the electrodes. The calculated electron transport coefficients are used as input for the classical fluid model, to investigate the inception and propagation of negative ionisation fronts in indium vapour at various E/N and vapour temperatures. We calculate the electron density, electric field, and velocity of ionisation fronts as a function of E/N and indium vapour temperature. The presence of indium atoms in the first ( 5 s 2 5 p ) 2 P 3 / 2 metastable state significantly affects the characteristics of the negative ionisation fronts. The transition from an avalanche into a negative ionisation front occurs faster with increasing indium vapour temperature, due to enhanced ionisation and more efficient production of electrons at higher vapour temperatures. For lower values of E/N, the electron density behind the streamer front, where the electric field is screened, does not decay as one might expect for atomic gases, but it could be increased due to the accumulation of low-energy electrons that are capable of initiating ionisation in the streamer interior.

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36

Ridley, B. K. "Ionisation waves in solids." Journal of Physics: Condensed Matter 2, no. 13 (April 2, 1990): 2941–52. http://dx.doi.org/10.1088/0953-8984/2/13/004.

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37

Parzynski, R. "Raman-enhanced multiphoton ionisation." Journal of Physics B: Atomic and Molecular Physics 20, no. 19 (October 14, 1987): 5035–50. http://dx.doi.org/10.1088/0022-3700/20/19/015.

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38

Aplin, K. L., and J. H. Williams. "Atmospheric ionisation in Snowdonia." Journal of Physics: Conference Series 301 (June 23, 2011): 012002. http://dx.doi.org/10.1088/1742-6596/301/1/012002.

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39

Clarke, C. J., and J. E. Dale. "Simulations of ionisation triggering." Proceedings of the International Astronomical Union 2, S237 (August 2006): 300–305. http://dx.doi.org/10.1017/s1743921307001639.

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AbstractWe review recent pilot simulations that incorporate feedback from ionising radiation in SPH calculations of star forming clouds. In the case that the ionising radiation source is located within the star forming cloud, the inhomogeneity of the cloud significantly modifies the way that feedback operates compared with spherically symmetric cloud models. Inflow/outflow behaviour develops, combining accretion down dense filaments and thermally driven outflows that can remove many times the binding energy of the parent cloud. If the ionising source is located external to the cloud, we find evidence for triggered star formation but conclude that it is hard to find unambiguous observational signatures that would distinguish “triggered” stars from those created spontaneously.

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40

Whitehouse, Andrew I. "Laser-enhanced ionisation spectrometry." TrAC Trends in Analytical Chemistry 16, no. 5 (May 1997): 292—XI. http://dx.doi.org/10.1016/s0165-9936(97)89788-9.

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41

Concina, B., S. Tomita, N. Takahashi, T. Kodama, S. Suzuki, K. Kikuchi, Y. Achiba, A. Gromov, J. U. Andersen, and P. Hvelplund. "Delayed ionisation of C76." International Journal of Mass Spectrometry 252, no. 2 (May 2006): 96–99. http://dx.doi.org/10.1016/j.ijms.2005.11.029.

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42

Roberts, A. D. "Laser Ionisation Mass Analysis." Analytica Chimica Acta 309, no. 1-3 (June 1995): 406. http://dx.doi.org/10.1016/0003-2670(95)90337-2.

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43

Concina, B., S. Tomita, J. U. Andersen, and P. Hvelplund. "Delayed ionisation of C70." European Physical Journal D 34, no. 1-3 (July 2005): 191–94. http://dx.doi.org/10.1140/epjd/e2005-00142-5.

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44

Reemtsma, Thorsten. "Flügel durch Elektrospray-Ionisation." Nachrichten aus der Chemie 52, no. 2 (February 2004): 217. http://dx.doi.org/10.1002/nadc.20040520250.

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45

Pérez, E., L. Cuesta, D. Axon, and A. Robinson. "Ionisation Structure of NGC 6543." Symposium - International Astronomical Union 180 (1997): 270. http://dx.doi.org/10.1017/s0074180900130888.

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We have obtained high spectral resolution, high signal-to-noise ratio longslit spectra of a sample of Planetary Nebulae with the purpose of studying their physical conditions, chemical composition and ionisation structure. In particular, we are interested in disentangling the effects of radiation and shock ionisation.

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46

PIETRZAK, KATARZYNA, and BEATA GUTAROWSKA. "The Effectiveness of Photocatalytic Ionisation Disinfection of Filter Materials." Polish Journal of Microbiology 62, no. 2 (2013): 131–39. http://dx.doi.org/10.33073/pjm-2013-018.

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The purpose of this study was to determine the effectiveness of photocatalytic ionisation as a disinfection method for filter materials contaminated by microorganisms, and to assess how air relative humidity (RH), time and microbe type influence the effectiveness of this disinfection. In the quantitative analysis of a used car air filter, bacterial contamination equalled 1.2 x 10(5) cfu/cm2, fungal contamination was 3.8 x 10(6) cfu/cm2, and the isolated microorganisms were Aspergillus niger, Bacillus megaterium, Cladosporium herbarum, Cryptococcus laurenti, Micrococcus sp., Rhodotorula glutinis and Staphylococcus cohnii. In the model experiment, three isolates (C. herbarum, R. glutinis, S. cohnii) and 3 ATCC species (A. niger, E. coli, S. aureus) were used for photocatalytic ionisation disinfection. The conditions of effective photocatalytic ionisation disinfection (R > or = 99.9%) were established as 2-3 h at RH = 77% (bacteria) and 6-24 h at RH = 53% (fungi). RH has an influence on the effectiveness of the photocatalytic disinfection process; the highest effectiveness was obtained for bacteria at RH = 77%, with results 5% higher than for RH = 49%. The studies show that the sensitivity of microorganisms to photocatalytic ionisation disinfection is ordered as follows: Gram-positive bacteria (S. cohnii, S. aureus), Gram-negative bacteria (E. coli), yeasts (R. glutinis), and moulds (C. herbarum, A. niger). Of all the mathematical models used for the description of death dynamics after photocatalytic ionisation disinfection, the Chick-Watson model is the most useful, but for more resistant microorganisms, the delayed Chick-Watson model is highly recommended. It therefore seems, that the presented disinfection method of photocatalytic ionisation can be successfully used to clean filtration materials.

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47

García-Rojas, Nancy Shyrley, Héctor Guillén-Alonso, Sandra Martínez-Jarquín, Abigail Moreno-Pedraza, Leonardo D. Soto-Rodríguez, and Robert Winkler. "Build, Share and Remix: 3D Printing for Speeding Up the Innovation Cycles in Ambient Ionisation Mass Spectrometry (AIMS)." Metabolites 12, no. 2 (February 17, 2022): 185. http://dx.doi.org/10.3390/metabo12020185.

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Ambient ionisation mass spectrometry (AIMS) enables studying biological systems in their native state and direct high-throughput analyses. The ionisation occurs in the physical conditions of the surrounding environment. Simple spray or plasma-based AIMS devices allow the desorption and ionisation of molecules from solid, liquid and gaseous samples. 3D printing helps to implement new ideas and concepts in AIMS quickly. Here, we present examples of 3D printed AIMS sources and devices for ion transfer and manipulation. Further, we show the use of 3D printer parts for building custom AIMS sampling robots and imaging systems. Using 3D printing technology allows upgrading existing mass spectrometers with relatively low cost and effort.

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48

Rodríguez-Barrera, M. I., Ch Helling, and K. Wood. "Environmental effects on the ionisation of brown dwarf atmospheres." Astronomy & Astrophysics 618 (October 2018): A107. http://dx.doi.org/10.1051/0004-6361/201832685.

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Context. Brown dwarfs emit bursts of Hα, white-light flares, and show radio flares and quiescent radio emission. They are suggested to form aurorae, similar to planets in the solar system, but much more energetic. All these processes require a source gas with an appropriate degree of ionisation, which, so far, is mostly postulated to be sufficient. Aims. We aim to demonstrate that the Galactic environment influences atmospheric ionisation, and that it hence amplifies or enables the magnetic coupling of the atmospheres of ultra-cool objects, like brown dwarfs and free-floating planets. Methods. We build on our previous work on thermal ionisation of ultra-cool atmospheres and explore the effect of environmental high-energy radiation on the degree of ionisation in the atmosphere. We consider the effect of photoionisation by Lyman-continuum radiation in three different environments: in the interstellar radiation field (ISRF), O and B stars in star-forming regions, and in white dwarf companions in binary systems. We apply our Monte Carlo radiation transfer code to investigate the effect of Lyman-continuum photoionisation for prescribed atmosphere structures for very low-mass objects. Results. The external radiation environment plays an important role for the atmospheric ionisation of very low-mass, ultra-cool objects. Lyman-continuum irradiation greatly increases the level of ionisation in the uppermost atmospheric regions. Our results suggest that a shell of an almost fully ionised atmospheric gas emerges for brown dwarfs in star-forming regions and brown dwarfs in white dwarf binary systems. As a consequence, brown dwarf atmospheres can be magnetically coupled, which is the presumption for chromospheric heating to occur and for aurorae to emerge. First tests for assumed chromosphere-like temperature values suggest that the resulting free-free X-ray luminosities are comparable with those observed from non-accreting brown dwarfs in star-forming regions.

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Mingozzi, M., G. Cresci, G. Venturi, A. Marconi, F. Mannucci, M. Perna, F. Belfiore, et al. "The MAGNUM survey: different gas properties in the outflowing and disc components in nearby active galaxies with MUSE." Astronomy & Astrophysics 622 (February 2019): A146. http://dx.doi.org/10.1051/0004-6361/201834372.

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We investigated the interstellar medium (ISM) properties of the disc and outflowing gas in the central regions of nine nearby Seyfert galaxies, all characterised by prominent conical or biconical outflows. These objects are part of the Measuring Active Galactic Nuclei Under MUSE Microscope (MAGNUM) survey, which aims to probe their physical conditions and ionisation mechanism by exploiting the unprecedented sensitivity of the Multi Unit Spectroscopic Explorer (MUSE), combined with its spatial and spectral coverage. Specifically, we studied the different properties of the gas in the disc and in the outflow with spatially and kinematically resolved maps by dividing the strongest emission lines in velocity bins. We associated the core of the lines with the disc, consistent with the stellar velocity, and the redshifted and the blueshifted wings with the outflow. We measured the reddening, density, ionisation parameter, and dominant ionisation source of the emitting gas for both components in each galaxy. We find that the outflowing gas is characterised by higher values of density and ionisation parameter than the disc, which presents a higher dust extinction. Moreover, we distinguish high- and low-ionisation regions across the portion of spatially resolved narrow-line region (NLR) traced by the outflowing gas. The high-ionisation regions characterised by the lowest [N II]/Hα and [S II]/Hα line ratios generally trace the innermost parts along the axis of the emitting cones where the [S III]/[S II] line ratio is enhanced, while the low-ionisation regions follow the cone edges and/or the regions perpendicular to the axis of the outflows, also characterised by a higher [O III] velocity dispersion. A possible scenario to explain these features relies on the presence of two distinct populations of line emitting clouds: one is optically thin to the radiation and is characterised by the highest excitation, while the other is optically thick and is impinged by a filtered, and thus harder, radiation field which generates strong low-excitation lines. The highest values of [N II]/Hα and [S II]/Hα line ratios may be due to shocks and/or a hard filtered radiation field from the active galactic nucleus.

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50

Das, JN. "Partial Wave Expansion of Three-particle Continuum. States in Hyperspherical Coordinates: Application to Ionisation Problems." Australian Journal of Physics 47, no. 6 (1994): 743. http://dx.doi.org/10.1071/ph940743.

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A partial wave expansion of three-particle continuum states has been developed using hyperspherical coordinates. An approximate three-particle continuum state appears which may be useful in electron-hydrogen atom ionisation studies. Further improvement in the result is also possible. The analysis may be easily extended for application to other three-body ionisation problems.

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