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Koichi Ohno - One of the best experts on this subject based on the ideXlab platform.
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outer valence ionic states of cr co 6 and η5 c5h5 co co 2 observed by two dimensional penning Ionization electron spectroscopy
Journal of Physical Chemistry A, 2009Co-Authors: Naoki Kishimoto, Koichi OhnoAbstract:Outer valence ionic states of Cr(CO)(6) and (eta(5)-C(5)H(5))Co(CO)(2) were investigated by means of Penning Ionization electron spectroscopy (PIES) upon collision with metastable He*(2(3)S) excited atoms as well as high-level ab initio molecular orbital calculations taking electron correlation effects into consideration. By the 2D measurement combining the collision-energy-resolved technique of the metastable atomic beam and electron spectroscopy, ionic-state-resolved measurement of collision energy dependence of partial Ionization Cross Sections (CEDPICS) was carried out. Because partial Penning Ionization Cross Sections can be connected to the spatial extent of corresponding molecular orbitals (MOs) outside the boundary surface of colliding He* atoms, different slopes of CEDPICS were related to anisotropic interaction around the MO region. The observed CEDPICS and PIES band intensity were consistent with the order of calculated ionic states.
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stereodynamics and outer valence ionic states of ferrocene in collisional Ionization with a he 23s metastable atom by two dimensional penning Ionization electron spectroscopy
Journal of Physical Chemistry A, 2009Co-Authors: Naoki Kishimoto, Koichi OhnoAbstract:Outer valence ionic states of ferrocene were investigated by means of Penning Ionization electron spectroscopy upon collision with metastable He*(2(3)S) excited atoms. By two-dimensional measurement combining electron spectroscopy and collision-energy-resolved technique of the metastable atomic beam, ionic-state-resolved measurements of collision energy dependence of partial Penning Ionization Cross Sections (CEDPICS) were carried out. Since the partial Penning Ionization Cross Sections can be connected with spatial extension of corresponding molecular orbitals (MOs) outside the boundary surface for the collision with He* atoms, different slope values of CEDPICS were related with stereodynamics in Penning Ionization as well as anisotropic interaction around the Ionization region: attractive interaction around ligand pi orbitals and repulsive interaction around ligand sigma orbtials and the metal atom. The observed negative collision energy dependence of Ionization Cross Sections for the first ((2)E(2)') and second ((2)A(1)') ionic states was consistent with configuration interactions suggested by ab initio MO calculations [J. Chem. Phys. 2002, 117, 6533], which is due to the strong electron correlation effects beyond the one-electron MO description.
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development of a cooled he 2s3 beam source for measurements of state resolved collision energy dependence of penning Ionization Cross Sections evidence for a stereospecific attractive well around methyl group in ch3cn
Journal of Chemical Physics, 2005Co-Authors: Takuya Horio, Naoki Kishimoto, Masakazu Yamazaki, Satoshi Maeda, T Hatamoto, Koichi OhnoAbstract:A low-temperature discharge nozzle source with a liquid-N2 circulator for He*(2S3) metastable atoms has been developed in order to obtain the state-resolved collision energy dependence of Penning Ionization Cross Sections in a low collision energy range from 20 to 80 meV. By controlling the discharge condition, we have made it possible to measure the collision energy dependence of partial Ionization Cross Sections (CEDPICS) for a well-studied system of CH3CN+He*(2S3) in a wide energy range from 20 to 350 meV. The anisotropic interaction potential energy surface for the present system was obtained starting from an ab initio model potential via an optimization procedure based on classical trajectory calculations for the observed CEDPICS. A dominant attractive well depth was found to be 423 meV (ca. 10kcal∕mol) at a distance of 3.20 A from the center of mass of CH3CN in the N-atom side along the CCN axis. In addition, a weak attractive well (ca. 0.9kcal∕mol) surrounding the methyl group (−CH3) has been found...
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classical trajectory calculations of collision energy dependence of penning Ionization Cross Sections for n2 and co by he 23s optimization of anisotropic model potentials
Chemical Physics Letters, 2002Co-Authors: Masakazu Yamazaki, Naoki Kishimoto, Satoshi Maeda, Koichi OhnoAbstract:Abstract Anisotropic potential energy surfaces were optimized for classical trajectory calculations in order to reproduce collision energy dependence of partial Penning Ionization Cross-Sections for N 2 and CO molecules with a He ∗ (2 3 S) atom. Ab initio model potentials using a Li(2 2 S) atom in place of a He ∗ (2 3 S) atom based on the similarity of valence electronic configurations were found to be successfully corrected by addition of negative terms including an exponential function combined with Legendre expansions. Optimized sets of parameters demonstrate that the most important correction terms are related to attractive interactions due to electron transfer from He ∗ (Li) to unoccupied molecular orbitals.
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classical trajectory calculations of collision energy dependence of total and partial penning Ionization Cross Sections for he 23s n2 he n2 e
Journal of Chemical Physics, 1999Co-Authors: Tetsuji Ogawa, Koichi OhnoAbstract:Classical trajectory calculations are performed for the Penning Ionization system He*(23S)+N2→He(1 1S)+N2+(X 2Σg+,A 2Πu,B 2Σu+)+e−. Anisotropic model potentials of He*(2 3S)+N2 are adapted to reproduce collision-energy dependence of ionic-state-resolved Ionization Cross Sections observed by two-dimensional Penning Ionization electron spectroscopy. Results of trajectory calculations are compared with those of ab initio potential surfaces obtained by Ishida. Opacity functions are demonstrated to be strongly dependent on ionic states, collision energy, and anisotropic varieties of trajectories.
Naoki Kishimoto - One of the best experts on this subject based on the ideXlab platform.
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outer valence ionic states of cr co 6 and η5 c5h5 co co 2 observed by two dimensional penning Ionization electron spectroscopy
Journal of Physical Chemistry A, 2009Co-Authors: Naoki Kishimoto, Koichi OhnoAbstract:Outer valence ionic states of Cr(CO)(6) and (eta(5)-C(5)H(5))Co(CO)(2) were investigated by means of Penning Ionization electron spectroscopy (PIES) upon collision with metastable He*(2(3)S) excited atoms as well as high-level ab initio molecular orbital calculations taking electron correlation effects into consideration. By the 2D measurement combining the collision-energy-resolved technique of the metastable atomic beam and electron spectroscopy, ionic-state-resolved measurement of collision energy dependence of partial Ionization Cross Sections (CEDPICS) was carried out. Because partial Penning Ionization Cross Sections can be connected to the spatial extent of corresponding molecular orbitals (MOs) outside the boundary surface of colliding He* atoms, different slopes of CEDPICS were related to anisotropic interaction around the MO region. The observed CEDPICS and PIES band intensity were consistent with the order of calculated ionic states.
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stereodynamics and outer valence ionic states of ferrocene in collisional Ionization with a he 23s metastable atom by two dimensional penning Ionization electron spectroscopy
Journal of Physical Chemistry A, 2009Co-Authors: Naoki Kishimoto, Koichi OhnoAbstract:Outer valence ionic states of ferrocene were investigated by means of Penning Ionization electron spectroscopy upon collision with metastable He*(2(3)S) excited atoms. By two-dimensional measurement combining electron spectroscopy and collision-energy-resolved technique of the metastable atomic beam, ionic-state-resolved measurements of collision energy dependence of partial Penning Ionization Cross Sections (CEDPICS) were carried out. Since the partial Penning Ionization Cross Sections can be connected with spatial extension of corresponding molecular orbitals (MOs) outside the boundary surface for the collision with He* atoms, different slope values of CEDPICS were related with stereodynamics in Penning Ionization as well as anisotropic interaction around the Ionization region: attractive interaction around ligand pi orbitals and repulsive interaction around ligand sigma orbtials and the metal atom. The observed negative collision energy dependence of Ionization Cross Sections for the first ((2)E(2)') and second ((2)A(1)') ionic states was consistent with configuration interactions suggested by ab initio MO calculations [J. Chem. Phys. 2002, 117, 6533], which is due to the strong electron correlation effects beyond the one-electron MO description.
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development of a cooled he 2s3 beam source for measurements of state resolved collision energy dependence of penning Ionization Cross Sections evidence for a stereospecific attractive well around methyl group in ch3cn
Journal of Chemical Physics, 2005Co-Authors: Takuya Horio, Naoki Kishimoto, Masakazu Yamazaki, Satoshi Maeda, T Hatamoto, Koichi OhnoAbstract:A low-temperature discharge nozzle source with a liquid-N2 circulator for He*(2S3) metastable atoms has been developed in order to obtain the state-resolved collision energy dependence of Penning Ionization Cross Sections in a low collision energy range from 20 to 80 meV. By controlling the discharge condition, we have made it possible to measure the collision energy dependence of partial Ionization Cross Sections (CEDPICS) for a well-studied system of CH3CN+He*(2S3) in a wide energy range from 20 to 350 meV. The anisotropic interaction potential energy surface for the present system was obtained starting from an ab initio model potential via an optimization procedure based on classical trajectory calculations for the observed CEDPICS. A dominant attractive well depth was found to be 423 meV (ca. 10kcal∕mol) at a distance of 3.20 A from the center of mass of CH3CN in the N-atom side along the CCN axis. In addition, a weak attractive well (ca. 0.9kcal∕mol) surrounding the methyl group (−CH3) has been found...
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classical trajectory calculations of collision energy dependence of penning Ionization Cross Sections for n2 and co by he 23s optimization of anisotropic model potentials
Chemical Physics Letters, 2002Co-Authors: Masakazu Yamazaki, Naoki Kishimoto, Satoshi Maeda, Koichi OhnoAbstract:Abstract Anisotropic potential energy surfaces were optimized for classical trajectory calculations in order to reproduce collision energy dependence of partial Penning Ionization Cross-Sections for N 2 and CO molecules with a He ∗ (2 3 S) atom. Ab initio model potentials using a Li(2 2 S) atom in place of a He ∗ (2 3 S) atom based on the similarity of valence electronic configurations were found to be successfully corrected by addition of negative terms including an exponential function combined with Legendre expansions. Optimized sets of parameters demonstrate that the most important correction terms are related to attractive interactions due to electron transfer from He ∗ (Li) to unoccupied molecular orbitals.
H Deutsch - One of the best experts on this subject based on the ideXlab platform.
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revised high energy behavior of the deutsch mark dm formula for the calculation of electron impact Ionization Cross Sections of atoms
International Journal of Mass Spectrometry, 2004Co-Authors: H Deutsch, K H Becker, P Scheier, T D MarkAbstract:Abstract We modified the Deutsch-Mark (DM) formula for the calculation of single atomic Ionization Cross Sections by replacing the previously used Gryzinsky-type energy dependence by a “scaled” ln( E )/ E energy dependence. This modified energy dependence yields, in the limit of high impact energies, the well-established Born–Bethe ln( E )/ E energy dependence, while reproducing, at lower impact energies, the DM Cross section function. The revised DM formula, whose energy dependence has been determined from a fitting procedure using reliable, measured Ionization Cross Sections for the atoms H, He, C, Ne, Mg, Al, and Ag, was subsequently used to calculate as an example Ionization Cross Sections for the atoms O, F, P, Ar, Ge, Kr, and Xe and excellent to very good agreement was found between the calculated and the measured Cross Sections for these atoms over a wide range of impact energies.
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Calculation of absolute electron-impact Ionization Cross-Sections of dimers and trimers
EDP Sciences, 2000Co-Authors: H Deutsch, K. Becker, T D MarkAbstract:We report calculations of the electron-impact Ionization Cross-Sections of selected dimers (homonuclear diatomic molecules) and trimers (homonuclear triatomic molecules) using a method which relies only on macroscopic quantities in conjunction with a "defect concept". The empirically determined defect describes the deviation of the cluster (dimer, trimer) Cross-Sections from a simple linear dependence on the cluster size. We compare the calculated Cross-Sections to experimental data for the dimers S2 and F2 and the trimer O3 and we present predictions for the Ionization Cross-Sections of Br2, I2, C2 and C3 for which no experimental data are available. Lastly, we extend the method to the calculation of Ionization Cross-Sections for the fullerenes C60 and C70
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theoretical determination of absolute electron impact Ionization Cross Sections of molecules
International Journal of Mass Spectrometry, 2000Co-Authors: H Deutsch, K. Becker, S Matt, T D MarkAbstract:Abstract Much emphasis has been devoted recently to the experimental determination of absolute electron-impact Ionization Cross Sections of molecules and radicals because of the importance of these Cross Sections in many applications (e.g. as input parameters to modeling codes for various purposes). Supporting theoretical calculations have been lagging behind to some extent. Because of the inherent complexity of such calculations, simplistic additivity rules and semiempirical methods have often been used in place of more rigorous calculation schemes, particularly in applications where a larger number of Cross section data were needed with reasonable precision. Although these methods have often proved to be quite successful as descriptive tools (i.e. reproducing existing experimental Ionization Cross Sections reasonably well), their ability to calculate Cross Sections for species for which no experimental data are available (predictive capabilities) tend to be limited or questionable. This topical review describes recent progress in the development of more rigorous approaches for the calculation of absolute electron-impact molecular Ionization Cross Sections. The main emphasis will be on the application of the semiclassical Deutsch–Mark (DM) formalism, which was originally developed for the calculation of atomic Ionization Cross Sections, to molecular targets, and on the binary–encounter–Bethe (BEB) method of Kim and Rudd. The latter is a simpler version of the more rigorous binary–encounter–dipole (BED) theory, which was also first developed for the calculation of atomic Ionization Cross Sections, and based on the methods developed by Khare and co-workers. Extensive comparisons between available experimental Cross Sections and the predictions of these theoretical models will be made for 31 molecules and free radicals (H 2 , N 2 , O 2 , S 2 , C 2 , C 3 , O 3 , H 2 O, NH 3 , CO 2 , CH 4 , CH 3 , CH 2 , CH, CF 4 , CF 3 , CF 2 , CF, NF 3 , NF 2 , NF, SiF 3 , SiF 2 , SiF, TiCl 4 , C 2 H 2 , C 2 H 6 , C 6 H 6 , SiF 6 , C 2 F 6 , CH 3 OH).
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application of the modified additivity rule to the calculation of electron impact Ionization Cross Sections of complex molecules
Journal of Physical Chemistry A, 1998Co-Authors: H Deutsch, Ralf Basner, K H Becker, M Schmidt, T D MarkAbstract:This paper describes the application of the modified additivity rule (MAR) to the calculation of total (counting) electron-impact Ionization Cross Sections of complex molecules with sum formulas of the form A{sub x},B{sub y}, A{sub x},B{sub y},C{sub z}, and A{sub p},B{sub s}C{sub t}D{sub u}. The MAR incorporates weighting factors for the contributions to the molecular Ionization Cross section from the Ionization Cross Sections of the constituent atoms, which depend explicitly on the atomic radii and the effective number of atomic electrons except for a few special cases (hydrides where the other constituent atom has a radius smaller than the radius of the H atom and species where both constituent atoms have radii smaller than the radius of the H atom), where the weighting factors depend only on the atomic radii, i.e., on geometric effects. A comprehensive comparison of the predictions of the modified additivity rule with available experimental data and with other theoretical predictions is presented.
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absolute total and partial electron impact Ionization Cross Sections of hexamethyldisiloxane
International Journal of Mass Spectrometry, 1998Co-Authors: Ralf Basner, Rudiger Foest, K. Becker, M Schmidt, H DeutschAbstract:Abstract We studied the electron impact Ionization of hexamethyldisiloxane (HMDSO), Si 2 O(CH 3 ) 6 , which is widely used in plasma-enhanced polymerization applications. Appearance energies and absolute partial Cross Sections for the formation of fragment ions with relative intensities >1% of the most abundant ion, the Si 2 O(CH 3 ) 5 + fragment ion, were measured in a high resolution double focusing sector field mass spectrometer with a modified ion extraction stage for electron energies from threshold to 100 eV. Dissociative Ionization was found to be the dominant process. The main Ionization channel removes a complete methyl group to produce the fragment ion Si 2 O(CH 3 ) 5 + with a Cross section of 1.7 × 10 −15 cm 2 at 70 eV. The stoichiometric and isotope composition of the various fragment ions was determined by using the high resolution ( m /Δ m = 40,000) of the mass spectrometer used in these studies. The methyl ion is formed with considerable excess kinetic energy, whereas all other fragment ions are formed with essentially no excess energy. The experimental total single Ionization Cross section of HMDSO (2.2 × 10 −15 cm 2 at 70 eV impact energy) is in good agreement with the result of a semiempirical calculation (2.1 × 10 −15 cm 2 at the same energy).
Bobby Antony - One of the best experts on this subject based on the ideXlab platform.
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study of elastic and inelastic Cross Sections by positron impact on inert gases
European Physical Journal D, 2018Co-Authors: Suvam Singh, Rahla Naghma, Jaspreet Kaur, Bobby AntonyAbstract:In this article, a modified computational method recently introduced is used for the calculation of total, positronium (Ps) formation and Ionization Cross Sections including direct and total Ionization Cross Sections for positron scattering from noble gases. The incident positron is assumed to have energies over a wide range from ~5 eV to 5 keV. The positron–atom interaction potential is developed under an optical potential framework and the computations of Cross Sections for each process are performed by introducing appropriate absorption thresholds. The calculated results obtained by employing this modified approach are found to be in reasonably good agreement with most of the existing data.
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calculation of total and Ionization Cross Sections for electron scattering by primary benzene compounds
Journal of Chemical Physics, 2016Co-Authors: Suvam Singh, Rahla Naghma, Jaspreet Kaur, Bobby AntonyAbstract:The total and Ionization Cross Sections for electron scattering by benzene, halobenzenes, toluene, aniline, and phenol are reported over a wide energy domain. The multi-scattering centre spherical complex optical potential method has been employed to find the total elastic and inelastic Cross Sections. The total Ionization Cross section is estimated from total inelastic Cross section using the complex scattering potential-Ionization contribution method. In the present article, the first theoretical calculations for electron impact total and Ionization Cross section have been performed for most of the targets having numerous practical applications. A reasonable agreement is obtained compared to existing experimental observations for all the targets reported here, especially for the total Cross section.
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electron impact Ionization Cross section of c2 c3 si2 si3 sic sic2 and si2c
Molecular Physics, 2013Co-Authors: Rahla Naghma, Bobby AntonyAbstract:Total Ionization Cross-Sections for C2, C3, Si2, Si3, SiC, SiC2 and Si2C molecules have been calculated by electron impact. Spherical complex optical potential formalism has been employed for obtaining the inelastic Cross-Sections for these molecules. Then by applying complex scattering potential-Ionization contribution method, total Ionization Cross-Sections are derived. These Cross-Sections are calculated in the energy range from Ionization threshold to 2 keV. There are no measurements available in the literature to the best of our knowledge with which our results can be compared. The results show a linear relationship between maximum Ionization Cross-section and square root of the ratio of polarizability to Ionization potential, depending on its atomicity. This gives a confirmation for the consistency of the data reported here. Present work is a maiden attempt to find electron impact Ionization Cross-section for these molecules, except for C2 and C3.
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electron impact total Ionization Cross Sections for simple bio molecules h2co hcooh and ch3cooh using icsp ic method
Journal of Physics: Conference Series, 2012Co-Authors: Harshad Bhutadia, Minaxi Vinodkumar, Bobby AntonyAbstract:In the present work we compute total Ionization Cross Sections for simple bio-molecules viz. formaldehyde, formic acid and acetic acid on electron impact. The total Ionization Cross Sections are extracted from total inelastic Cross section using Improved Complex Scattering Potential-Ionization contribution method.
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electron impact total Ionization Cross Sections for halogens and their hydrides
International Journal of Mass Spectrometry, 2010Co-Authors: Minaxi Vinodkumar, Rucha Dave, Harshad Bhutadia, Bobby AntonyAbstract:Abstract Calculation for electron impact total Ionization Cross Sections on halogen atoms (F, Cl, Br and I) and their hydrides (HF, HCl, HBr and HI) are performed employing Spherical Complex Optical Potential and Complex Optical Potential-Ionization contribution formalisms. In this article we are presenting data for energies ranging from above threshold to 2000 eV. Our results are compared with available experimental and theoretical data wherever available. It is found that the present result gives a better account of the Ionization Cross Sections.
T D Mark - One of the best experts on this subject based on the ideXlab platform.
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revised high energy behavior of the deutsch mark dm formula for the calculation of electron impact Ionization Cross Sections of atoms
International Journal of Mass Spectrometry, 2004Co-Authors: H Deutsch, K H Becker, P Scheier, T D MarkAbstract:Abstract We modified the Deutsch-Mark (DM) formula for the calculation of single atomic Ionization Cross Sections by replacing the previously used Gryzinsky-type energy dependence by a “scaled” ln( E )/ E energy dependence. This modified energy dependence yields, in the limit of high impact energies, the well-established Born–Bethe ln( E )/ E energy dependence, while reproducing, at lower impact energies, the DM Cross section function. The revised DM formula, whose energy dependence has been determined from a fitting procedure using reliable, measured Ionization Cross Sections for the atoms H, He, C, Ne, Mg, Al, and Ag, was subsequently used to calculate as an example Ionization Cross Sections for the atoms O, F, P, Ar, Ge, Kr, and Xe and excellent to very good agreement was found between the calculated and the measured Cross Sections for these atoms over a wide range of impact energies.
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Calculation of absolute electron-impact Ionization Cross-Sections of dimers and trimers
EDP Sciences, 2000Co-Authors: H Deutsch, K. Becker, T D MarkAbstract:We report calculations of the electron-impact Ionization Cross-Sections of selected dimers (homonuclear diatomic molecules) and trimers (homonuclear triatomic molecules) using a method which relies only on macroscopic quantities in conjunction with a "defect concept". The empirically determined defect describes the deviation of the cluster (dimer, trimer) Cross-Sections from a simple linear dependence on the cluster size. We compare the calculated Cross-Sections to experimental data for the dimers S2 and F2 and the trimer O3 and we present predictions for the Ionization Cross-Sections of Br2, I2, C2 and C3 for which no experimental data are available. Lastly, we extend the method to the calculation of Ionization Cross-Sections for the fullerenes C60 and C70
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theoretical determination of absolute electron impact Ionization Cross Sections of molecules
International Journal of Mass Spectrometry, 2000Co-Authors: H Deutsch, K. Becker, S Matt, T D MarkAbstract:Abstract Much emphasis has been devoted recently to the experimental determination of absolute electron-impact Ionization Cross Sections of molecules and radicals because of the importance of these Cross Sections in many applications (e.g. as input parameters to modeling codes for various purposes). Supporting theoretical calculations have been lagging behind to some extent. Because of the inherent complexity of such calculations, simplistic additivity rules and semiempirical methods have often been used in place of more rigorous calculation schemes, particularly in applications where a larger number of Cross section data were needed with reasonable precision. Although these methods have often proved to be quite successful as descriptive tools (i.e. reproducing existing experimental Ionization Cross Sections reasonably well), their ability to calculate Cross Sections for species for which no experimental data are available (predictive capabilities) tend to be limited or questionable. This topical review describes recent progress in the development of more rigorous approaches for the calculation of absolute electron-impact molecular Ionization Cross Sections. The main emphasis will be on the application of the semiclassical Deutsch–Mark (DM) formalism, which was originally developed for the calculation of atomic Ionization Cross Sections, to molecular targets, and on the binary–encounter–Bethe (BEB) method of Kim and Rudd. The latter is a simpler version of the more rigorous binary–encounter–dipole (BED) theory, which was also first developed for the calculation of atomic Ionization Cross Sections, and based on the methods developed by Khare and co-workers. Extensive comparisons between available experimental Cross Sections and the predictions of these theoretical models will be made for 31 molecules and free radicals (H 2 , N 2 , O 2 , S 2 , C 2 , C 3 , O 3 , H 2 O, NH 3 , CO 2 , CH 4 , CH 3 , CH 2 , CH, CF 4 , CF 3 , CF 2 , CF, NF 3 , NF 2 , NF, SiF 3 , SiF 2 , SiF, TiCl 4 , C 2 H 2 , C 2 H 6 , C 6 H 6 , SiF 6 , C 2 F 6 , CH 3 OH).
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application of the modified additivity rule to the calculation of electron impact Ionization Cross Sections of complex molecules
Journal of Physical Chemistry A, 1998Co-Authors: H Deutsch, Ralf Basner, K H Becker, M Schmidt, T D MarkAbstract:This paper describes the application of the modified additivity rule (MAR) to the calculation of total (counting) electron-impact Ionization Cross Sections of complex molecules with sum formulas of the form A{sub x},B{sub y}, A{sub x},B{sub y},C{sub z}, and A{sub p},B{sub s}C{sub t}D{sub u}. The MAR incorporates weighting factors for the contributions to the molecular Ionization Cross section from the Ionization Cross Sections of the constituent atoms, which depend explicitly on the atomic radii and the effective number of atomic electrons except for a few special cases (hydrides where the other constituent atom has a radius smaller than the radius of the H atom and species where both constituent atoms have radii smaller than the radius of the H atom), where the weighting factors depend only on the atomic radii, i.e., on geometric effects. A comprehensive comparison of the predictions of the modified additivity rule with available experimental data and with other theoretical predictions is presented.
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a modified additivity rule for the calculation of electron impact Ionization Cross section of molecules abn
International Journal of Mass Spectrometry and Ion Processes, 1997Co-Authors: H Deutsch, K H Becker, T D MarkAbstract:Abstract This paper describes a modified additivity rule for the calculation of electron impact Ionization Cross-Sections of molecules and radicals of the form ABn(n = 1–6). This additivity rule incorporates weighting factors for the contributions to the molecular Ionization Cross-Sections from the Ionization Cross-Sections of the constituent atoms, which depend explicitly on the atomic radii and the effective number of atomic electrons. In a few special cases (hydrides where the other constituent atom has a radius smaller than the radius of the H atom and species where both constituent atoms have radii smaller than the radius of the H atom), the weighting factors can be simplified, so that they depend only on the atomic radii, i.e. on geometric effects. A comprehensive comparison of the predictions of this new modified additivity rule with available experimental data and with other theoretical predictions is presented.
