Journal articles: 'IONIZATON'

1

Oda, Toshiatsu, Shinichi Namba, Ken Takiyama, and Utaro Furukane. "Fast Numerical Calculation for a Set of Nonlinear Rate Equations: Application to Rapid Ionizaton Phase in Plasma." Japanese Journal of Applied Physics 44, no. 11 (November 9, 2005): 8118–24. http://dx.doi.org/10.1143/jjap.44.8118.

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2

Wiederholt, Erwin, Volker Fahrney, and Dorothea Behrens. "A modular apparatus for demonstrating gas chromatography using serial coupling of a thermal conductivity and flame ionizaton detector." Journal of Chemical Education 67, no. 2 (February 1990): 181. http://dx.doi.org/10.1021/ed067p181.

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3

Manchado, A., F. Prada, L. Stanghellini, and N. Panagia. "Sub-arcsecond near-IR imaging and long-slit spectroscopy of NGC 7027." Symposium - International Astronomical Union 180 (1997): 256. http://dx.doi.org/10.1017/s0074180900130748.

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We report sub-arcsecond narrow band imaging in the lines of H2 2.1218 μm, Brγ 2.16 μm, [Fe II] 1.664 μm of the Planetary Nebulae NGC 7027. Data were obtained at the 3.5 m telescope at Calar Alto Observatory (Spain), using MAGIC. A false color image was produced by combining these three narrow band images. Thus, and due to extraordinary seeing (0″.6 arcsecond) conditions, allow us to reveal the morphology of the excited molecular and ionized gas. The Brγ and the [Fe II] images allowed us to study the structure of the ionized gas at slightly different excitation levels, according to the ionization potentials of the ions involved in the corresponding transitions (13.6 eV to ionize hydrogen, versus 17.4 eV for iron ionizaton). Since NGC 7027 is a high excitation nebula, the iron is readily double– ionized in the hotter regions, thus what we really see in the [Fe II] image is the low–intermediate excitation zones. By studying the [Fe II] and Brγ images together we infer that: the (non–reddened) low–ionization gas morphology consists of a regular, smooth ring reminder of a projected cylindrical structure. In addition to a brightness level that is at least thirty times the brightness of the maximum [Fe II] emission, the ionized hydrogen image exhibit a strong brightness gradient between the mentioned ring and the outer regions, and the emission is comparatively negligible outside the ring–like feature of about 12 × 10 arcsec (the measures refer to the major and minor axes of the ellipse–like shape). The [Fe II] morphology is less so ring–like and regular, and it seems to indicate smaller scale structure, such as clumps and filaments, at the resolution scale–level. The dishomogeneity in the [Fe II] emission could be ascribed to gradients in the elemental distribution, as well (and more probably so) as to the plasma temperature and density inhomogeneities. The H2 molecular image completely embeds the ionized gas zones, up to a size of about 16 × 11 arcsec. The smaller size refers here to the waist of the markedly bipolar shape, similar to a projected peanut; the larger size is the dimension of the two main lobes. The highest brightness through the molecular filters corresponds to the inner ring, slightly less extended than the ionized one, and to an outer envelope that is not seen in the ionized gas, and has a maximum diagonal extension of about 24 arcsec. Spatially resolved low resolution spectra (R 200) were obtained in the H and K band.

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4

Afaneh, Feras, and Horst Schmidt-Böcking. "Imaging of strong field dissociative single and double ionization channels of N2O." International Journal of Modern Physics B 31, no. 29 (November 7, 2017): 1750215. http://dx.doi.org/10.1142/s0217979217502150.

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In this paper, we study single and double ionizations of N2O in a short elliptically polarized 800 nm laser pulse using the COLTRIMS technique. The molecular-frame photoelectron angular distribution and the ion sum-momentum distribution of single and double ionizations of N2O molecules are reported for the single ionization dissociative channel NO[Formula: see text] + N and the double ionization dissociative channel NO[Formula: see text] + N[Formula: see text]. The ionizations of multiple orbitals for the two studied dissociative channels were identified via studying the orientation dependent ionization rates for their KERs. The results show that the shape of the ionizing orbitals governs the single and double ionization processes of N2O.

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Madunil, Siddihalu Lakshitha, Totaro Imasaka, and Tomoko Imasaka. "Resonant and non-resonant femtosecond ionization mass spectrometry of organochlorine pesticides." Analyst 145, no. 3 (2020): 777–83. http://dx.doi.org/10.1039/c9an01861a.

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6

Muchall, Heidi M., and Nick H. Werstiuk. "Ionization potentials of nitriles — Photoelectron spectra of succinonitrile and glutaronitrile." Canadian Journal of Chemistry 84, no. 9 (September 1, 2006): 1124–31. http://dx.doi.org/10.1139/v06-141.

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The He(I) photoelectron spectra of succinonitrile (1) and glutaronitrile (2), both with extensive overlap of ionization bands in the low-energy region, are reported. To assign ionizations, we studied the conformational behaviour and resulting ionization energy dependence of 1 and 2 computationally with the B3LYP/6-31+G(d) model chemistry based on the fact that it reliably reproduces the ionization potentials of eleven mono- and di-nitriles, both saturated and unsaturated. The correlation of proton affinities with observed ionization potentials of 1, 2, and malononitrile establishes the orbital sequence of four C≡N π orbitals followed by two nitrogen lone pair orbitals as the highest occupied molecular orbitals for all three compounds.Key words: photoelectron spectrum, ionization potential, conformational dependence, nitrile, DFT.

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7

Fowe, Emmanuel Penka, and André Dieter Bandrauk. "Nonlinear time-dependent density functional theory studies of the ionization of CO2 by ultrashort intense laser pulses." Canadian Journal of Chemistry 87, no. 7 (July 2009): 1081–89. http://dx.doi.org/10.1139/v09-074.

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Time-dependent density functional theory (TDDFT) studies of the ionization of CO2 by intense laser pulses (3.50 × 1014, 1.40 × 1015, 2.99 × 1015, and 1.25 × 1016 W/cm2) at 800 nm (ω = 0.0584 au) are presented in the nonlinear nonpertubative regime. Special emphasis is placed on elucidating molecular orbital orientation and various peak-intensities effects on the ionization processes. The results reveal that molecular orbital ionizations are strongly sensitive to their symmetry and the laser intensities. Most notably, we found that with a proper choice of the laser intensity (3.5 × 1014 W/cm2), the sensitivity is strong enough such that the nature and symmetry of the highest occupied molecular orbital (HOMO) can be directly probed and visualized from the angular dependence of laser-induced ionization. At higher intensities, ionization is found to occur also from inner orbitals, thus complicating the imaging of simple orbitals. A time-dependent electron-localization function (TDELF) is used to get a visual insight on the time evolution process of the electron density.

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8

Bartnik, Andrzej, Wojciech Skrzeczanowski, Henryk Fiedorowicz, Przemysław Wachulak, Tomasz Fok, Łukasz Węgrzyński, and Roman Jarocki. "Photoionized plasmas induced in molecular gases by extreme ultraviolet and X-ray pulses." EPJ Web of Conferences 167 (2018): 03003. http://dx.doi.org/10.1051/epjconf/201816703003.

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In this work a laser-produced plasma (LPP) source was used to create low temperature plasmas. An extreme ultraviolet and soft X-ray (EUV/SXR) radiation pulse was used for ionization of molecular gases, injected into a vacuum chamber synchronously with the EUV/SXR pulse. Energies of photons exceeding 100 eV were sufficient for dissociative ionization, ionization of atoms or even ions. The resulting photoelectrons had also enough energy for further ionizations or excitations. Time resolved UV/VIS spectra, corresponding to single charged ions, molecules and molecular ions, were recorded. For spectral lines, corresponding to radiative transitions in F II and S II ions, electron temperature was calculated based on a Boltzmann plot method. Numerical simulations of the molecular spectra were fitted to the experimental spectra allowing for determination of vibrational and rotational temperatures.

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9

Mah, K. R., F. W. Dalby, and C. W. Barnard. "Polarization dependence of resonant multiphoton ionizations on 1S0 and 1,3D2 states in atomic mercury." Canadian Journal of Physics 66, no. 1 (January 1, 1988): 1–6. http://dx.doi.org/10.1139/p88-001.

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The polarization dependences of some resonant multiphoton ionizations in atomic mercury have been measured with a broadband (bandwidth ≈ 1.5 cm−1) multimode dye laser at moderate light intensities (≈ 500 MW∙cm−2). The multiphoton processes studied were the absorption of four photons to a resonant 1S0, 1D2, or 3D2 level by one-photon ionization. Complete saturation of the one-photon ionization step results in the ionization of all atoms excited to the resonant level. Because of the saturation of the ionization step, the polarization dependence of the four-photon excitation to the resonant level is measured. The theory developed by Dalby et al. is shown to give good agreement with the experiment when it is used to calculate the polarization dependence of the multiphoton transition to the resonant level. For the 6d1D2 resonance, distortions in the polarization dependence and an unusual linewidth dependence on the light polarization were observed. We relate these observations to the alternating current Stark effect and to the production of the third harmonic of the laser light in the focal volume.

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10

Sharma, Kamlesh Kumar, and Sanjeev Saxena. "Electron (Positron) Impact Ionization of Xenon." Indian Journal of Applied Research 3, no. 11 (October 1, 2011): 454–55. http://dx.doi.org/10.15373/2249555x/nov2013/145.

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11

Lee, Hae-Rim, Sunil Kochhar, and Soon-Mi Shim. "Comparison of Electrospray Ionization and Atmospheric Chemical Ionization Coupled with the Liquid Chromatography-Tandem Mass Spectrometry for the Analysis of Cholesteryl Esters." International Journal of Analytical Chemistry 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/650927.

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The approach of two different ionization techniques including electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was tested for the analysis of cholesteryl esters (CEs). The retention time (RT), signal intensity, protonated ion, and product ion of CEs were compared between ESI and APCI. RT of CEs from both ionizations decreased with increasing double bonds, while it increased with longer carbon chain length. The ESI process generated strong signal intensity of precursor ions corresponding to [M+Na]+and [M+NH4]+regardless of the number of carbon chains and double bonds in CEs. On the other hand, the APCI process produced a protonated ion of CEs [M+H]+with a weak signal intensity, and it is selectively sensitive to detect precursor ions of CEs with unsaturated fatty acids. The ESI technique proved to be effective in ionizing more kinds of CEs than the APCI technique.

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Zavilopulo, A., and O. Shpenik. "Electron-Impact Mass Spectrometry of PTCDA Molecules in the Gas Phase." Ukrainian Journal of Physics 64, no. 1 (January 30, 2019): 3. http://dx.doi.org/10.15407/ujpe64.1.3.

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The complete and dissociative ionizations of a 3,4,9,10-perylene-tetracarboxylic-dianhydride (C24H8O6, PTCDA) molecule in the gas phase have been studied, by using electron-impact mass spectrometry in an energy interval of 5–90 eV. The molecule is found to decay into the following fragment ions: the perylene core C20H8+ and its half C10H4+, as well as CO+, CO2+ , and O+ ions. The energy dependences of the cross-sections of the complete ionization of a PTCDA molecule and its fragment ions are analyzed. The energy of the complete ionization of a PTCDA molecule and the energies, at which its fragments appear, are determined. The temperature dependences of the formation of the most intensive fragment ions are measured, by using 80-eV electrons in a temperature interval of 320–500 K.

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13

YU, CHIN-HUI, JEN-SHIANG K. YU, and WEI-CHEN CHEN. "THE ESTIMATIONS OF INNER-SHELL IONIZATION ENERGIES FOR ALKYL HALIDES: A DESIGNATED SINGLE-CONFIGURATION CASSCF APPROACH AND ADVANCED CORRECTION." Journal of Theoretical and Computational Chemistry 03, no. 01 (March 2004): 103–15. http://dx.doi.org/10.1142/s021963360400088x.

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Based on the Franck–Condon principle, vertical ionization energies regarding the inner-shell valence electrons of alkyl halides and their unsaturated analogues were evaluated with a designated single-configuration complete active self-consistent field (CASSCF) approach as well as the advanced correction with configuration interaction. Excitations corresponding to the elimination of one electron from a specific molecular orbital of these species were calculated by the deviation between the energy of the SCF-optimized neutral structure and of its cation. The freezing over the outer orbitals with identical symmetry was achieved while performing the CASSCF ionization calculation for the inner orbitals. These energy evaluations utilized Pople's 6-31G*, 6-311G** and Roos' ANO basis sets. Computed results agreed well with the experimental data. The characters for the molecular orbitals of corresponding vertical ionizations could be qualitatively assigned by the MOLDEN visualization program.

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14

Aznabayev, D. T., A. K. Bekbaev, I. S. Ishmukhamedov, V. I. Korobov, and A. B. Turmaganbet. "Nonrelativistic ionization energy levels of a helium atom." Physical Sciences and Technology 2, no. 1 (2015): 59–65. http://dx.doi.org/10.26577/2409-6121-2015-2-1-59-65.

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15

PEDOCCHI, L., G. ROVIDA, and N. RUSSO. "XPS CHEMICAL SHIFTS FOR CO ADSORBED ON Ni(100): A THEORETICAL STUDY." Surface Review and Letters 02, no. 05 (October 1995): 563–68. http://dx.doi.org/10.1142/s0218625x95000522.

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Starting from the observed chemical shift of C-1s and O-1s ionization potentials (IP), reported in the literature for the adsorption of CO on Ni (100), and correlated to the different CO adsorption sites at different coverages, we have carried out a theoretical investigation, using a first-principle density-functional method, to calculate ionization energies for adsorbed CO in the atop and bridge sites. In our approach, the Ni (100) surface was simulated with clusters of up to nine metal atoms of different geometry, in order to test the two adsorption sites. For each cluster, the CO adsorption geometry was optimized and the O-1s and C-1s ionizations were calculated. The main result was that the (O-1s–C-1s) difference was very well reproduced even with clusters of modest size, thus confirming the possibility to use this value as a structure-sensitive parameter.

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16

Bartnik, A., W. Skrzeczanowski, H. Fiedorowicz, P. Wachulak, and T. Fok. "Low-temperature plasmas induced in nitrogen by extreme ultraviolet (EUV) pulses." Laser and Particle Beams 36, no. 1 (January 25, 2018): 76–83. http://dx.doi.org/10.1017/s0263034617000982.

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AbstractIn this work, a comparative study of low-temperature plasmas, induced in a gaseous nitrogen by photoionization of the gas using two different irradiation systems, was performed. Both systems were based on laser-produced Xe plasmas, emitting intense extreme ultraviolet (EUV) radiation pulses in a wide wavelength range. The essential difference between the systems concerned formation of the EUV beam. The first one utilized a dedicated ellipsoidal mirror for collecting and focusing of the EUV radiation. This way a high radiation fluence could be obtained for ionization of the N2 gas injected into the vacuum chamber. The second system did not contain any EUV collector. In this case, the nitrogen to be ionized was injected into the vicinity of the Xe plasma. In both cases, energies of emitted photons were sufficient for dissociative ionization, ionization of atoms or even ions. The resulting photoelectrons had also sufficiently high energy for further ionizations or excitations. Low-temperature plasmas, created this way, were investigated by spectral measurements in the EUV, ultraviolet (UV) and visible (VIS) spectral ranges. Time-resolved UV/VIS spectra, corresponding to single-charged ions, molecules, and molecular ions, were recorded. Numerical simulations of the molecular spectra were performed allowing one to estimate vibrational and rotational temperatures of plasmas created using both irradiation systems.

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Sharma, Kamlesh Kumar, and Sanjeev Saxena. "DCS and TICS for Ionization of Noble gas Atom." Indian Journal of Applied Research 3, no. 5 (October 1, 2011): 42–43. http://dx.doi.org/10.15373/2249555x/may2013/184.

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18

Jintai Liang, Jintai Liang, Ruozhou Zhang Ruozhou Zhang, Xiaomeng Ma Xiaomeng Ma, Yueming Zhou Yueming Zhou, and Peixiang Lu Peixiang Lu. "Angular momentum distribution in strong-field frustrated tunneling ionization." Chinese Optics Letters 16, no. 4 (2018): 040202. http://dx.doi.org/10.3788/col201816.040202.

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19

Riveros, Alberto, and Gustavo Castellano. "Gaussian ϕ(ρz) curves: Comparison with other models." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 2 (August 12, 1990): 192–93. http://dx.doi.org/10.1017/s0424820100134557.

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X ray characteristic intensity Ii , emerging from element i in a bulk sample irradiated with an electron beam may be obtained throughwhere the function ϕi(ρz) is the distribution of ionizations for element i with the mass depth ρz, ψ is the take-off angle and μi the mass absorption coefficient to the radiation of element i.A number of models has been proposed for ϕ(ρz), involving several features concerning the interaction of electrons with matter, e.g. ionization cross section, stopping power, mean ionization potential, electron backscattering, mass absorption coefficients (MAC’s). Several expressions have been developed for these parameters, on which the accuracy of the correction procedures depends.A great number of experimental data and Monte Carlo simulations show that the general shape of ϕ(ρz) curves remains substantially the same when changing the incident electron energy or the sample material. These variables appear in the parameters involved in the expressions for ϕ(ρz). A good description of this function will produce an adequate combined atomic number and absorption correction.

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20

Gore, M. G., P. Greasley, G. McAllister, and C. I. Ragan. "Mammalian inositol monophosphatase: the identification of residues important for the binding of Mg2+ and Li+ ions using fluorescence spectroscopy and site-directed mutagenesis." Biochemical Journal 296, no. 3 (December 15, 1993): 811–15. http://dx.doi.org/10.1042/bj2960811.

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The fluorescence properties of residue Trp-219 in inositol monophosphatase are sensitive to the ionization of neighbouring groups. The pH-dependent changes in the fluorescence emission intensity and wavelength of maximum emission appear to arise as the result of two separate ionizations in the proximity of Trp-219, namely due to the ionization of His-217 and Cys-218. By studying the curve of fluorescence intensity against pH, given by the mutants Cys-218→Ala or His-217→Gln, the pK of His-217 was determined to be 7.54 and the pK of Cys-218 was estimated to be about 8.2. These mutants have altered kinetic parameters for catalytic Mg2+ ions and inhibitory Mg2+ and Li+ ions. The Cys-218→Ala mutant enzyme is not subject to inhibition by concentrations of Mg2+ ions up to 400 mM and has a specific activity of 156% of the maximum obtainable activity of the native enzyme. The His-217→Gln mutant enzyme shows reduced sensitivity to inhibition by Mg2+ and Li+ ions, and has a specific activity of 110% of that obtainable for the native enzyme.

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21

de Avillez, Miguel A., Gervásio J. Anela, and Dieter Breitschwerdt. "Variability of the adiabatic parameter in monoatomic thermal and non-thermal plasmas." Astronomy & Astrophysics 616 (August 2018): A58. http://dx.doi.org/10.1051/0004-6361/201832948.

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Context. Numerical models of the evolution of interstellar and integalactic plasmas often assume that the adiabatic parameter γ (the ratio of the specific heats) is constant (5/3 in monoatomic plasmas). However, γ is determined by the total internal energy of the plasma, which depends on the ionic and excitation state of the plasma. Hence, the adiabatic parameter may not be constant across the range of temperatures available in the interstellar medium. Aims. We aim to carry out detailed simulations of the thermal evolution of plasmas with Maxwell–Boltzmann and non-thermal (κ and n) electron distributions in order to determine the temperature variability of the total internal energy and of the adiabatic parameter. Methods. The plasma, composed of H, He, C, N, O, Ne, Mg, Si, S, and Fe atoms and ions, evolves under collisional ionization equilibrium conditions, from an initial temperature of 109 K. The calculations include electron impact ionization, radiative and dielectronic recombinations and line excitation. The ionization structure was calculated solving a system of 112 linear equations using the Gauss elimination method with scaled partial pivoting. Numerical integrations used in the calculation of ionization and excitation rates are carried out using the double-exponential over a semi-finite interval method. In both methods a precision of 10−15 is adopted. Results. The total internal energy of the plasma is mainly dominated by the ionization energy for temperatures lower than 8 × 104 K with the excitation energy having a contribution of less than one percent. In thermal and non-thermal plasmas composed of H, He, and metals, the adiabatic parameter evolution is determined by the H and He ionizations leading to a profile in general having three transitions. However, for κ distributed plasmas these three transitions are not observed for κ < 15 and for κ < 5 there are no transitions. In general, γ varies from 1.01 to 5/3. Lookup tables of the γ parameter are presented as supplementary material.

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22

MOTOYAMA, Akira, and Keishi KIHARA. "Principle and Applications of DESI (Desorption Electrospray Ionization): A Brief Review." Journal of the Mass Spectrometry Society of Japan 65, no. 3 (2017): 98–101. http://dx.doi.org/10.5702/massspec.s17-09.

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23

Twesten, R. D. "Phase Identification and Mapping Based on Valence Loss EELS and ELNES." Microscopy Today 17, no. 3 (May 2009): 16–19. http://dx.doi.org/10.1017/s1551929500050069.

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Much of analytical TEM is based on elemental analysis of core-shell ionizations and their role in electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDS). In these techniques, integrals of the primary or secondary ionization signals (typically over many tens of eV in energy) are used to measure and map the elemental composition of probed sample areas.In contrast, present-day STEM EELS systems are able to reveal spectral details with resolution in the range 0.1-1.0 eV. This means that EELS provides access to electronic structure and response information that goes beyond the simple elemental composition information of the integrated core-loss signals.

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Vairamanp, M., M. S. Rajeev, and G. K. Viswanadha Rao. "Acetone chemical ionization studies part V: Formation of (phenol + acetone)+· under chemical ionizationt." Organic Mass Spectrometry 27, no. 1 (January 1992): 57–58. http://dx.doi.org/10.1002/oms.1210270115.

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Shpenik, O. B., M. M. Erdevdy, P. P. Markush, J. E. Kontros, and I. V. Chernyshova. "Electron Impact Excitation and Ionization of Sulfur, Selenium, and Tellurium Vapors." Ukrainian Journal of Physics 60, no. 3 (March 2015): 217–24. http://dx.doi.org/10.15407/ujpe60.03.0217.

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Iwayama, Hiroshi, Masanari Nagasaka, Ichiro Inoue, Shigeki Owada, Makina Yabashi, and James R. Harries. "Demonstration of Transmission Mode Soft X-ray NEXAFS Using Third- and Fifth-Order Harmonics of FEL Radiation at SACLA BL1." Applied Sciences 10, no. 21 (November 5, 2020): 7852. http://dx.doi.org/10.3390/app10217852.

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We demonstrate the applicability of third- and fifth-order harmonics of free-electron laser (FEL) radiation for soft X-ray absorption spectroscopy in the transmission mode at SACLA BL1, which covers a photon energy range of 20 to 150 eV in the fundamental FEL radiation. By using the third- and fifth-order harmonics of the FEL radiation, we successfully recorded near-edge X-ray absorption fine structure (NEXAFS) spectra for Ar 2p core ionization and CO2 C 1s and O 1s core ionizations. Our results show that the utilization of third- and fifth-order harmonics can significantly extend the available photon energies for NEXAFS spectroscopy using an FEL and opens the door to femtosecond pump-probe NEXAFS using a soft X-ray FEL.

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YUAN, LI, and PING HE. "INFLUENCE OF SONOCHEMISTRY ON SINGLE-BUBBLE SONOLUMINESCENCE." Modern Physics Letters B 19, no. 28n29 (December 20, 2005): 1711–14. http://dx.doi.org/10.1142/s0217984905010281.

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Spherical oscillation of an acoustically levitated gas bubble in water was simulated numerically to elucidate the phenomenon of single-bubble sonoluminescence (SBSL). A refined hydro-chemical model was used, which took into account the processes of water vapor evaporation and condensation, mass diffusion, and chemical reactions. The numerical results show significant water vapor dissociations but rather low degrees of ionizations. A widely accepted weakly ionized gas model is then used to compute the light emission. Contrary to earlier predictions without chemical reactions, the present calculated light spectra are generally too small and the pulses are too short to fit to recent experimental results within stable SBSL range. To solve this contradiction, the electrostatic interactions of the ionized gases are included, which is shown to lower the ionization potentials of gas species in the bubble significantly.

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Kotera, Masatoshi, Ryoji Ijichi, Takafumi Fujiwara, Hiroshi Suga, and David B. Wittry. "A Simulation of Electron Scattering in Metals and its Application for Scanning Electron Microscopy." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 420–21. http://dx.doi.org/10.1017/s0424820100180859.

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In a recent research, the scanning electron microscope(SEM) has been shown to provide spatial resolution of less than 0.5nm. With the knowledge of the ultimate resolution or the factor which controls the resolution, it is possible to optimize the specimen preparation method and the choice of various electron beam parameters (eg. acceleration voltage etc.) For a precise discussion of the SEM image, it is necessary to take into account not only the signal (electron) production and the propagation in a specimen and its emission from the surface, but also electron trajectories in vacuum toward the detector. However, electron scattering process in the specimen does not depend on the detection system, and the resolution is mainly attributed to the spatial distribution of the electron emission from the specimen surface. Here, we focused on the electron scattering mechanisms in metals and developed a Monte Carlo simulation model of electron trajectories. Also, this simulation is applied to evaluate a compositional contrast in the SEM.In the present study electron interactions with atomic potential, inner-shell electrons, conduction electrons are taken into account. Cross sections calculated by the present model are shown in Fig.1 for [l]elastic scattering, [2]inner-shell (1s, 2s, 2p for Al) electron ionization, [3]conduction electron ionization through non-radiative plasmon decay, and [4] stable plasmon excitation in the conduction band electrons for Al. For the elastic scattering, the Mott cross section is used. For inner-shell electron ionizations by an electron collision, the Gryzinski equation is used. In order to express the plasmon-electron interaction in a free electron gas at the conduction band, the Lindhard treatment is used. This treatment is based on the random phase approximation in the dielectric response function of metals. The cross section is shown in a unit of the inverse mean free path. The cross sections for conduction electron ionization and the plasmon excitation agree with the data of Tung, Ashley, and Ritchie. Cross sections for inner-shell electron ionization, which Tung et al. have derived using the generalized oscillator strength, are also shown in Fig.1 for a comparison.

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Qiang Chen, Qiang Chen, Jiansheng Liu Jiansheng Liu, Wentao Li Wentao Li, Aihua Deng Aihua Deng, Wentao Wang Wentao Wang, Ye Tian Ye Tian, and Cheng Wang Cheng Wang. "Investigations of ionization-induced injection of laser wake field acceleration using phenomenological model." Chinese Optics Letters 11, s2 (2013): S23501–323504. http://dx.doi.org/10.3788/col201311.s23501.

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W. Becker, W. Becker, and D. B. Milosevic D. B. Milosevic. "Quantum-orbit theory of low-energy above-threshold ionization on and off axis." Chinese Optics Letters 13, no. 7 (2015): 070006–70010. http://dx.doi.org/10.3788/col201513.070006.

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Маурчев, Евгений, Evgeniy Maurchev, Юрий Балабин, Yuriy Balabin, Алексей Германенко, Aleksey Germanenko, Евгения Михалко, Evgeniya Mikhalko, Борис Гвоздевский, and Boris Gvozdevsky. "Calculating the ionization rate induced by GCR and SCR protons in Earth’s atmosphere." Solar-Terrestrial Physics 5, no. 3 (September 30, 2019): 68–74. http://dx.doi.org/10.12737/stp-53201908.

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This paper explores the applied use of the RUSCOSMICS software package [http://ruscosmics.ru] designed to simulate propagation of primary cosmic ray (CR) particles through Earth’s atmosphere and collect information about characteristics of their secondary component. We report the results obtained for proton fluxes with energy distributions corresponding to the differential spectra of galactic CR (GCR) and solar CR (SCR) during ground level enhancement (GLE) events GLE65 and GLE67. We examine features of the geometry of Earth’s atmosphere, parametrization methods, and describe a primary particle generator. The typical energy spectra of electrons obtained both for GCR and for GLE65 provide information that allows us to quantitatively estimate the SCR contribution to the enhancement of secondary CR fluxes. We also present altitude dependences of ionization rate for GCR and both the GLE events for several geomagnetic cutoff rigidity values. The conclusion summarizes and discusses the prospects for future research.

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NAITO, Susumu, Shuji YAMAMOTO, Makoto TAKEMURA, and Jun ITO. "ICONE19-43150 NEW SMALL SODIUM LEAK DETECTION SYSTEM, (I) MOVING FLUID IONIZATION DETECTOR." Proceedings of the International Conference on Nuclear Engineering (ICONE) 2011.19 (2011): _ICONE1943. http://dx.doi.org/10.1299/jsmeicone.2011.19._icone1943_52.

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33

Ottolinf, Luisa, and C. Hawthorne. "An investigation of SIMS matrix effects on H, Li and B ionization in tourmaline." European Journal of Mineralogy 11, no. 4 (July 16, 1999): 679–90. http://dx.doi.org/10.1127/ejm/11/4/0679.

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34

Aoyama, Takafumi, Koki Okazaki, Chikara Ito, Hideki Harano, Kenichi Watanabe, and Tetsuo Iguchi. "ICONE15-10323 DEVELOPMENT OF SODIUM LEAK DETECTION TECHNOLOGY USING LASER RESONANCE IONIZATION MASS SPECTROMETRY." Proceedings of the International Conference on Nuclear Engineering (ICONE) 2007.15 (2007): _ICONE1510. http://dx.doi.org/10.1299/jsmeicone.2007.15._icone1510_163.

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35

Jonauskas, Valdas. "Electron-impact double ionization of the carbon atom." Astronomy & Astrophysics 620 (December 2018): A188. http://dx.doi.org/10.1051/0004-6361/201834303.

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Electron-impact single- and double-ionization cross sections and Maxwellian rate coefficients are presented for the carbon atom. Scaling factors are introduced for the electron-impact excitation and ionization cross sections obtained in the distorted wave (DW) approximation. It is shown that the scaled DW cross sections provide good agreement with measurements for the single ionization of the C atom and C1+ ion. The direct double-ionization (DDI) process is studied using a multi-step approach. Ionization–ionization, excitation–ionization–ionization, and ionization–excitation–ionization branches are analyzed. It is demonstrated that the three-step processes contribute ≼40% of the total DDI cross sections for the case where one of the electrons takes all of the excess energy after the first ionization process.

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36

Feng, Li-Qiang, and Li Liu. "Control of the half-cycle harmonic emission process for generating the intense and ultrashort single attosecond pulses (SAPs)." Zeitschrift für Naturforschung A 75, no. 11 (November 26, 2020): 903–11. http://dx.doi.org/10.1515/zna-2020-0170.

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AbstractIn this paper, the half-cycle harmonic generation process has been controlled by using the asymmetric inhomogeneous chirped pulse combined with the ultraviolet (UV) pulse. It is found that by properly optimizing the chirps and chirp delays of the fundamental two-color pulse, the optimal negative and positive half-cycle laser profiles for the harmonic cutoff extension can be obtained. Further, with the introduction of the negative and positive inhomogeneous effect, respectively, the harmonic cutoff from the negative and positive half-cycle laser profiles can be further improved. Next, with the assistance of the UV pulse, the harmonic intensity can be enhanced due to the UV resonance ionization. Moreover, the single and double UV photon resonance ionizations are much better for generating the higher harmonic intensity. As a result, the stronger and broader harmonic plateaus with the larger harmonic cutoff can be obtained, which can support the generation of the high-intensity ultrashort attosecond pulses with the pulse durations of sub-45 as.

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37

Graham, Caroline E., Keith Brocklehurst, Richard W. Pickersgill, and Martin J. Warren. "Characterization of retinaldehyde dehydrogenase 3." Biochemical Journal 394, no. 1 (January 27, 2006): 67–75. http://dx.doi.org/10.1042/bj20050918.

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RALDH3 (retinal dehydrogenase 3) was characterized by kinetic and binding studies, protein engineering, homology modelling, ligand docking and electrostatic-potential calculations. The major recognition determinant of an RALDH3 substrate was shown to be an eight-carbon chain bonded to the aldehyde group whose kinetic influence (kcat/Km at pH 8.5) decreases when shortened or lengthened. Surprisingly, the β-ionone ring of all-trans-retinal is not a major recognition site. The dissociation constants (Kd) of the complexes of RALDH3 with octanal, NAD+ and NADH were determined by intrinsic tryptophan fluorescence. The similarity of the Kd values for the complexes with NAD+ and with octanal suggests a random kinetic mechanism for RALDH3, in contrast with the ordered sequential mechanism often associated with aldehyde dehydrogenase enzymes. Inhibition of RALDH3 by tri-iodothyronine binding in competition with NAD+, predicted by the modelling, was established kinetically and by immunoprecipitation. Mechanistic implications of the kinetically influential ionizations with macroscopic pKa values of 5.0 and 7.5 revealed by the pH-dependence of kcat are discussed. Analogies with data for non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase from Streptococcus mutans, together with the present modelled structure of the thioacyl RALDH3, suggest (a) that kcat characterizes deacylation of this intermediate for specific substrates and (b) the assignment of the pKa of the major ionization (approximating to 7.5) to the perturbed carboxy group of Glu280 whose conjugate base is envisaged as supplying general base catalysis to attack of a water molecule. The macroscopic pKa of the minor ionization (5.0) is considered to approximate to that of the carboxy group of Glu488.

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HIRAOKA, Kenzo. "Ionization Methods Originated from Penning Ionization." Journal of the Mass Spectrometry Society of Japan 65, no. 3 (2017): 107–13. http://dx.doi.org/10.5702/massspec.s17-08.

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39

Tarelin, Anatolii, and Iryna Annopolska. "Wet Steam Flow Ionization and Prospects to Practically Apply Electrical Discharge Devices in Turbo Installations." Journal of Mechanical Engineering 22, no. 2 (June 30, 2019): 4–13. http://dx.doi.org/10.15407/pmach2019.02.004.

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40

Peng, Mian, and Lihua Bai. "Scaling law in nonsequential double ionization by counter-rotating two-color circularly polarized laser fields." Chinese Optics Letters 18, no. 11 (2020): 110201. http://dx.doi.org/10.3788/col202018.110201.

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41

Petrović, V., H. Delibašić, and I. Petrović. "Tunneling Ionization Study of Linear Molecules in Strong-Field Laser Pulses." Studia Universitatis Babeș-Bolyai Physica 65, no. 1-2 (December 30, 2020): 57–68. http://dx.doi.org/10.24193/subbphys.2020.07.

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"We theoretically studied photoionization of atoms and molecules in the frame of Perelomov-Popov-Terent’ev (PPT) and Ammosov-Delone-Krainov (ADK) theories. Strong-field single ionization of two diatomic molecules, N_2 and O_2, are studied and compared to Ar and Xe atoms, using an 800 nm Ti:sapphire laser in the 3×〖10〗^13 to 1×〖10〗^15 Wcm^(-2) intensity range. To eliminate disagreement between theoretical and experimental findings in a low intensity fields (~6×〖10〗^13 Wcm^(-2)), we considered the influence of shifted ionization potential. Including these effects in the ionization rates, we numerically solved rate equations in order to determine an expression for the ionization yields. The use of modiﬁed ionization potential showed that the ionization yields will actually decrease below values predicted by original (uncorrected) formulas. This paper will discuss the causes of this discrepancy. Keywords: tunneling ionization, ionization rate, ionization yield, molecules. "

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42

Schweig, Armin, and Werner Zittlau. "Semi-empirical pertci ionization spectra of some cumulenes and cumulene-like systems. Low-energy non-koopmans' ionizations." Chemical Physics 103, no. 2-3 (April 1986): 375–82. http://dx.doi.org/10.1016/0301-0104(86)80038-6.

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Okumura, Akihiko, Yasuaki Takada, Susumu Watanabe, Hiroaki Hashimoto, Naoya Ezawa, Yasuo Seto, Yasuo Takayama, et al. "In-Line Reactions and Ionizations of Vaporized Diphenylchloroarsine and Diphenylcyanoarsine in Atmospheric Pressure Chemical Ionization Mass Spectrometry." Journal of The American Society for Mass Spectrometry 27, no. 7 (April 20, 2016): 1219–26. http://dx.doi.org/10.1007/s13361-016-1394-0.

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44

Axner, O., and T. Berglind. "Determination of Ionization Efficiencies of Excited Atoms in a Flame by Laser-Enhanced Ionization Spectrometry." Applied Spectroscopy 43, no. 6 (August 1989): 940–52. http://dx.doi.org/10.1366/0003702894204029.

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State-specific ionization efficiencies for excited Li and Na atoms in acetylene/air flames have been determined. The ionization efficiencies, i.e., the probability that the excited atoms ionize instead of returning to the ground state, are determined by relating collision-assisted Laser-Enhanced Ionization (LEI) signals from various excited states with laser-induced photoionization signals. The ionization efficiencies are found to decrease (from being one at the ionization limit) almost monotonically as the lower atoms are excited. The most striking feature, however, is that the decrease of the ionization efficiency values is generally found to be less than the decrease of the Boltzmann factor, exp(- δE/kT), when the energy difference, δE, between the excited state and the ionization limit is increased. The ionization efficiencies are found to be close to unity for states with δE < kT and approximately 50% for states with δE ≈ 2.5 kT ( np ≈ 6 p). For the lower states, the ionization efficiencies are found to be approximately five times larger than the Boltzmann factor.

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45

Busman, Mark. "Quantitation of Mycotoxins Using Direct Analysis in Real Time Mass Spectrometry (DART-MS)." Journal of AOAC INTERNATIONAL 101, no. 3 (May 1, 2018): 643–46. http://dx.doi.org/10.5740/jaoacint.17-0338.

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Abstract Ambient ionization represents a new generation of MS ion sources and is used for the rapid ionization of small molecules under ambient conditions. The combination of ambient ionization and MS allows the analysis of multiple food samples with simple or no sample treatment or in conjunction with prevailing sample preparation methods. Two ambient ionization methods, desorptive electrospray ionization (DESI) and direct analysis in real time (DART) have been adapted for food safety application. Both ionization techniques provide unique advantages and capabilities. DART has been used for a variety of qualitative and quantitative applications. In particular, mycotoxin contamination of food and feed materials has been addressed by DART-MS. Applications to mycotoxin analysis by ambient ionization MS and particularly DART-MS are summarized.

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46

Kumar, Rajeev, SP Sharma, and Ravinder Sharma. "Electron impact ionization cross sections of hydrogen fluoride molecule." European Journal of Mass Spectrometry 26, no. 3 (December 6, 2019): 195–203. http://dx.doi.org/10.1177/1469066719893230.

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Partial and total ionization cross sections of hydrogen fluoride molecule are determined from the ionization threshold to high energy (5 KeV) by using a modified Jain–Khare semiempirical approach. Partial single and double differential cross sections with their sums (total) through direct and dissociative ionization have been also evaluated at fixed primary electron energies 100 eV, 200 eV, and 500 eV. There is no other data for partial ionization cross sections and differential ionization cross sections for comparison. In this paper, the total ionization cross sections data have compared with available experimental data and/or with other theoretical data which are available from intermediate to high energy. It is found that the present result gives a better account for the ionization cross sections up to higher energies.

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47

Wang, P., J. J. MacFarlane, and G. A. Moses. "Effects of multiple ionization on the Kα spectrum of aluminum in intense lithium beam experiments." Laser and Particle Beams 13, no. 2 (June 1995): 191–200. http://dx.doi.org/10.1017/s0263034600009319.

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The effect of multiple ionization on Kα spectra is investigated for aluminum targets irradiated by intense lithium beams. Multiple ionization cross sections have been calculated using a formulation incorporating single-electron ionization probability in the binomial distribution. In contrast to conventional binary-encounter approximation (BEA) theory, the single-electron ionization probabilities for each atomic shell have been calculated using a combination of modified plane-wave Born approximation (MPWBA) and an empirical effective interaction radius which is dependent on both the target ion and the projectile. Our calculations show that the effect of multiple inner-shell ionization on aluminum Kα spectra observed in intense lithium beam experiments is important. Multiple ionization effects become less important as the target ionization state increases. Nevertheless, even for highly ionized species up through Be-like Al multiple ionization effects can be significant and must be considered in the analysis of spectra obtained in intense Li beam-plasma interaction experiments.

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48

KRAINOV, V. P. "THEORY OF BARRIER-SUPPRESSION IONIZATION OF ATOMS." Journal of Nonlinear Optical Physics & Materials 04, no. 04 (October 1995): 775–98. http://dx.doi.org/10.1142/s0218863595000343.

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The theoretical description of the ionization of an atom (ion) by external electromagnetic radiation up to now concerned two alternative situations; multiphoton ionization and tunneling ionization. For both cases the formulas describing the ionization probability when the intensity of the laser field is not too strong are well known. However, if the field is strong, then there exists a new channel; the so-called barrier-suppression (or above-barrier) ionization of the atom. How does this process occur? It is obvious that barrier-suppression ionization and sub-barrier tunneling ionization by low-frequency laser field transform smoothly into one another as the field strength F is varied near the value of the barrier-suppression field F BSI . This paper contains a review of various theoretical approaches developed during the last few years, especially analytical considerations. Some new semi-analytical expressions for ionization rates, energy and angular distributions of ejected electrons are also derived.

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Fengzhen Feng, Fengzhen Feng, and Lihua Bai Lihua Bai. "Carrier-envelope-phase effect in nonsequential double ionization of Ar atoms by few-cycle laser pulses." Chinese Optics Letters 16, no. 6 (2018): 063201. http://dx.doi.org/10.3788/col201816.063201.

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50

Kemmo, S., V. Ollilainen, Lampi A-M, and V. Piironen. "Determination of stigmasterol hydroperoxides using high-performance liquid chromatography-mass spectrometry with atmospheric pressure chemical ionization." Czech Journal of Food Sciences 22, SI - Chem. Reactions in Foods V (January 1, 2004): S144—S146. http://dx.doi.org/10.17221/10639-cjfs.

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A new specific method using high-performance liquid chromatography-mass spectrometry (HPLC-MS) for the detection of stigmasterol hydroperoxides was developed. Hydroperoxides of stigmasterol were obtained by photo-oxidation (90 min) in the presence of methylene blue as a sensitizer. The separation was performed using normal-phase chromatographic conditions. The MS detection was carried out with an ion-trap mass spectrometer using atmospheric pressure chemical ionization (APCI) and positive ion mode. Stigmasterol hydroperoxides were seen to produce no protonated molecular ions [M + H]+ but instead fragments representing loss of one or two water molecules [M – H2O + H]+, [M – 2H2O + H]+, loss of hydrogen peroxide [M – H2O2 + H]+ or loss of hydrogen peroxide and water [M – H2O2 – H2O + H]+. The results showed that positional isomers of hydroperoxides had different fragmentation patterns and relative ion abundances. On the other hand anomeric isomers had more similar fragmentation. As a conclusion the method developed showed to be a useful tool for investigation the oxidation mechanism of sterols.

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Journal articles on the topic 'IONIZATON'

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