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Kevin J. Ross

Bio: Kevin J. Ross is an academic researcher. The author has contributed to research in topics: X-ray photoelectron spectroscopy & Photoemission spectroscopy. The author has an hindex of 7, co-authored 8 publications receiving 629 citations.

Papers
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Journal ArticleDOI
TL;DR: An electrostatic lens system which compensates for chromatic aberration has been tested in an electron spectrometer and the results indicate that this lens is suitable for comparisons of peak intensities in electron impact spectra.
Abstract: An electrostatic lens system which compensates for chromatic aberration has been tested in an electron spectrometer. The results indicate that this lens is suitable for comparisons of peak intensities in electron‐impact spectra. Relative intensities in vibrational progressions that belong to a single electronic transition have been studied in N2, CO, and NH3 and found to be nearly independent of the scattering angle. Electron‐impact spectra have been reported for helium, nitrogen, oxygen, argon, nitric oxide, nitrous oxide, ammonia, water vapor, carbon dioxide, ethylene, acetylene, and benzene at electron kinetic energies between 33 and 100 eV. Spectral regions of special interest are encountered in CO2 and C6H6. At excitation energies of 7–10 eV in CO2 a change in intensity distribution, attributed to transition from an electric‐quadrupole to an electric‐dipole spectrum, is observed as the kinetic energy is raised. In the case of C6H6 a change in the spectrum with angle is encountered which strongly sugg...

410 citations

Journal ArticleDOI
TL;DR: The electron impact spectrum of ethylene has been determined using a high-resolution electron spectrometer as discussed by the authors, and the intensity distribution obtained at 200-V electron kinetic energies agrees well with previous measurements made with 33-kV and ultraviolet-absorption measurements except in the region of the 7.45-V transition.
Abstract: The electron‐impact spectrum of ethylene has been determined using a high‐resolution electron spectrometer. The intensity distribution obtained at 200‐V electron kinetic energies agrees well with previous measurements made with 33‐kV electron kinetic energies, and ultraviolet‐absorption measurements except in the region of the 7.45‐V transition. This discrepancy is attributed to a quadrupole transition which occurs in this region.

52 citations

Journal ArticleDOI
TL;DR: In this article, the vacuum ultra-violet photoelectron spectrum of the CS molecule formed by electrodeless discharge of carbon disulphide or CO/rare gas mixtures is reported.
Abstract: The vacuum ultra-violet photoelectron spectrum of the CS molecule formed by electrodeless discharge of carbon disulphide or carbon disulphide/rare gas mixtures is reported. Four bands corresponding to the first four ionization potentials are observed, with associated vibrational fine structure in each case. The ionizing transitions responsible for these bands are assigned by comparison with the results of a CNDO calculation of CS+ and with the calculated and observed values for N2 and CO.

45 citations

Journal ArticleDOI
TL;DR: In this paper, a phase-sensitive detection technique, which enhances the relative signals from transient species present in a discharge system, is described and discussed, and two additional new states of O+2 which are present in the O2(1Δg) spectrum compared with O 2(3Σ-g) are identified as 2 Δg and 2 Δu with the aid of restricted open shell INDO-SCF calculations including the effect of configuration interaction.
Abstract: The vacuum ultra-violet photoelectron spectrum of O2(3Σ–g) and O2(1Δg) obtained using He I radiation, is presented. A phase-sensitive detection technique, which enhances the relative signals from transient species present in a discharge system, is described and discussed. The two additional new states of O+2 which are present in the O2(1Δg) spectrum compared with O2(3Σ–g) are identified as 2Δg and 2Φu with the aid of restricted open shell INDO-SCF calculations including the effect of configuration interaction. The energies of the 2Φu and 2Δg states are ∼6.59 and 7.72 eV respectively above that of the X2Πg ionic state. The bond lengths of these two states and of the 2Σ–g state have been obtained by comparison of observed band intensities with those determined by a Franck–Condon calculation, using a procedure which is described. These bond lengths are ∼1.40, 1.33 and 1.30 A for the 2Φu, 2Δg and 2Σ–g states respectively. The He II spectrum showed a further new state of O+2 which is tentatively identified as 2Δu. Higher states of O+2 which have been observed in ESCA studies are also assigned.

33 citations

Journal ArticleDOI
TL;DR: In this paper, a perturbation by the 6p′ 1P state has been observed in the 61S0→m1P1 series, and relative cross sections and oscillator strengths have been calculated from the intensity data at 300 eV and zero scattering angle.
Abstract: Electron‐impact spectra of mercury vapor have been investigated at incident electron energies between 50 and 300 eV. An intensity anomaly (expected from previous studies of atomic spectra) has been observed in the 61S0 → m1P1 series due to a perturbation by the 6p′ 1P state. Relative cross sections and oscillator strengths have been calculated from the intensity data at 300 eV and zero scattering angle.

31 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the Bethe theory has been updated with a number of new developments which need to be included in that body of material, such as the ${z}^{3}$ effect and the stopping power for particles at extreme relativistic energies.
Abstract: Since the appearance of the title paper, a number of new developments have occurred which need to be included in that body of material. We present additional remarks and clarifications which supplement and update numerous aspects of the Bethe theory discussed in the earlier paper. We also bring the bibliography up to date. Plasma stopping power, the ${z}^{3}$ effect, and stopping power for particles at extreme relativistic energies are among the new topics included. We make several comments on Fano's earlier review article, Ann. Rev. Nucl. Sci. 13, 1 (1963).

1,233 citations

Journal ArticleDOI
George J. Schulz1
TL;DR: In this article, the energies, configuration, and other properties of resonances (also called "compound states" and "temporary negative ions") in diatomic molecules are presented in the form of tables and energy level diagrams.
Abstract: In this review we present the energies, configuration, and other properties of resonances (also called "compound states" and "temporary negative ions") in diatomic molecules. Much of the information is presented in the form of tables and energy level diagrams. Vibrational, rotational, and electronic excitation are discussed whenever these processes have given information on resonances; often these excitation processes proceed via resonances. The paper is divided according to molecular species (${\mathrm{H}}_{2}$, ${\mathrm{N}}_{2}$, CO, NO, ${\mathrm{O}}_{2}$), but the main conclusions are discussed by the nature of the processes involved.

923 citations

01 Jan 1972
TL;DR: In this paper, the Bethe theory has been updated with a number of new developments which need to be included in that body of material, such as the ${z}^{3}$ effect and the stopping power for particles at extreme relativistic energies.
Abstract: Since the appearance of the title paper, a number of new developments have occurred which need to be included in that body of material. We present additional remarks and clarifications which supplement and update numerous aspects of the Bethe theory discussed in the earlier paper. We also bring the bibliography up to date. Plasma stopping power, the ${z}^{3}$ effect, and stopping power for particles at extreme relativistic energies are among the new topics included. We make several comments on Fano's earlier review article, Ann. Rev. Nucl. Sci. 13, 1 (1963).

832 citations

Journal ArticleDOI
TL;DR: An electrostatic lens system which compensates for chromatic aberration has been tested in an electron spectrometer and the results indicate that this lens is suitable for comparisons of peak intensities in electron impact spectra.
Abstract: An electrostatic lens system which compensates for chromatic aberration has been tested in an electron spectrometer. The results indicate that this lens is suitable for comparisons of peak intensities in electron‐impact spectra. Relative intensities in vibrational progressions that belong to a single electronic transition have been studied in N2, CO, and NH3 and found to be nearly independent of the scattering angle. Electron‐impact spectra have been reported for helium, nitrogen, oxygen, argon, nitric oxide, nitrous oxide, ammonia, water vapor, carbon dioxide, ethylene, acetylene, and benzene at electron kinetic energies between 33 and 100 eV. Spectral regions of special interest are encountered in CO2 and C6H6. At excitation energies of 7–10 eV in CO2 a change in intensity distribution, attributed to transition from an electric‐quadrupole to an electric‐dipole spectrum, is observed as the kinetic energy is raised. In the case of C6H6 a change in the spectrum with angle is encountered which strongly sugg...

410 citations

Journal ArticleDOI
TL;DR: In this paper, a new quantum chemical approach for ab initio calculations of electronic spectra of molecular systems is applied to the molecules ethene, trans‐1,3‐butadiene, and trans‐trans‐1.3,5−hexatriene.
Abstract: A newly proposed quantum chemical approach for ab initio calculations of electronic spectra of molecular systems is applied to the molecules ethene, trans‐1,3‐butadiene, and trans‐trans‐1,3,5‐hexatriene. The method has the aim of being accurate to better than 0.5 eV for excitation energies and is expected to provide structural and physical data for the excited states with good reliability. The approach is based on the complete active space (CAS) SCF method, which gives a proper description of the major features in the electronic structure of the excited state, independent of its complexity, accounts for all near degeneracy effects, and includes full orbital relaxation. Remaining dynamic electron correlation effects are in a subsequent step added using second order perturbation theory with the CASSCF wave function as the reference state. The approach is here tested in a calculation of the valence and Rydberg excited singlet and triplet states of the title molecules, using extended atomic natural orbital (ANO) basis sets. The ethene calculations comprised the two valence states plus all singlet and triplet Rydberg states of 3s, 3p, and 3d character, with errors in computed excitation energies smaller than 0.13 eV in all cases except the V state, for which the vertical excitation energy was about 0.4 eV too large. The two lowest triplet states and nine singlet states were studied in butadiene. The largest error (0.37 eV) was found for the 2 1Bu state. The two lowest triplet and seven lowest singlet states in hexatriene had excitation energies in error with less than 0.17 eV.

401 citations