Erratum: “Cross section and asymmetry parameter calculation for sulfur 1s photoionization of SF6” [J. Chem. Phys. <b>111</b>, 5344 (1999)]

Poliakoff

The Journal of Chemical Physics

et al. 2001

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We present results on the energy dependence of the vibrational branching ratio for the bending mode in CO 2 3 u Ϫ1 photoionization. Specifically, we determine the v ϩ ϭ(0,1,0)/v ϩ ϭ(0,0,0) intensity ratio by detecting dispersed fluorescence from the electronically excited photoions. The results exhibit large deviations over a very wide energy range, 18Ͻh exc Ͻ190 eV. Production of the v ϩ ϭ(0,1,0) level of the ion from the v 0 ϭ(0,0,0) ground state is forbidden by symmetry, and while observations of such features are well established in photoelectron spectroscopy, their appearance is normally ascribed to vibronic coupling in the ionic hole state. In this case, we find that such explanations fail to account for the energy dependence of the branching ratio. These deviations indicate that the continuum photoelectron participates in transferring oscillator strength to the nominally forbidden vibrational transition. A theoretical framework is developed for interpreting the experimental data, and Schwinger variational calculations are performed. These calculations demonstrate that the continuum electron is responsible for the observation of the excited bending mode as well as its energy dependence. This is an intrachannel effect that is best described as photoelectron-induced vibronic symmetry breaking. This appears to be a general phenomenon, and it may be useful in illuminating connections between bond angle and photoionization spectroscopies. The magnitude of these deviations display the utility of vibrationally resolved studies, and the extent over which these changes occur underscores the necessity of broad range studies to elucidate slowly varying characteristics in photoionization continua.

Section: B Calculated Resultsmentioning

confidence: 99%

“…͑8͒ are then used to compute the orientationally averaged cross sections in the usual manner. 35 Finally, we comment on how the nominally forbidden transitions to the v ϩ ϭ(0,1,0) level become allowed, and even enhanced. In Eq.…”

Section: ͑7͒mentioning

confidence: 99%

Excitation of the symmetry forbidden bending mode in molecular photoionization

Poliakoff

The Journal of Chemical Physics

et al. 2001

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The Journal of Chemical Physics

“…3-38 and references therein͒. Earlier calculations of the continuum spectrum employed the multiple-scattering ͑MS-X␣͒ formalism, 39,40 while the Schwinger variational iterative method 41,42 ͑SVIM͒ has been recently used for obtaining ab initio cross sections and angular distribution data for the valence 43 and C 1s ͑Ref. 44͒ ionizations at the frozen core Hartree-Fock ͑FCHF͒ level.…”

Section: Introductionmentioning

confidence: 99%

Photoionization cross section and angular distribution calculations of carbon tetrafluoride

Toffoli

Stener

Fronzoni

et al. 2006

Correlation in the photoionization dynamics of carbon tetrafluoride is studied in the framework of the time-dependent density-functional theory (TDDFT) approach by employing a multicentric basis set expansion of the scattering wave function linear combination of atomic orbitals (LCAO) TDDFT. Results obtained with the statistical average of orbital potentials and LB94 exchange-correlation (xc) potentials are compared with photoabsorption, photoionization, and electron-scattering experiments as well as with past theoretical calculations. Inadequacies in both the V(xc) parametrizations employed have been suggested from the analysis of the intensity plots for the D2A1 ionization. The formation of resonant scattering states in selected continuum channels has been studied through the analysis of the dipole-prepared scattering wave function; our findings are then compared with results of electron-scattering calculations. Overall, the LCAO-TDDFT results highlight the effectiveness of the approach for the calculation of the unbound spectrum of fairly large molecules.

“…With the aim to provide a more detailed picture of the photoionization properties of the ethane molecule, we have decided to study the outer-and inner-valence ionization processes employing our single-channel frozen-core HartreeFock (SCFCHF) approximation, based on the Schwinger variational method with Padé corrections [25]. The method has already been applied with considerable success to the study of core ionizations [25,26], valence ionizations [27][28][29], and electron-molecule collisions [30,31].…”

Section: Introductionmentioning

confidence: 99%

“…The method has already been applied with considerable success to the study of core ionizations [25,26], valence ionizations [27][28][29], and electron-molecule collisions [30,31]. The SCFCHF we use is essentially a one-electron method, thus we are unable to account for the multitude of many-body (MB) effects that are inherently displayed in the complexity of the electron-molecule interactions both at low and high energies [32].…”

Section: Introductionmentioning

confidence: 99%

Cross-section and asymmetry-parameter calculations for the outer- and inner-valence photoionization of ethane

2004

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We have computed cross sections and asymmetry parameters for the outer- and inner-valence photoionization of ethane using the Schwinger variational method with Pade corrections. The calculated total cross section is found to be in rather good agreement with the available electron-impact and photoabsorption measurements. One-electron resonant processes in the (1e(g))(-1), (3a(1g))(-1), and (2a(1g))(-1) ionization channels were examined comparing resonant states predicted from the virtual orbitals of a minimum basis set self-consistent-field (MBS-SCF) calculations with scattering resonances found using a local model potential for the electron-molecule interaction. The analysis of the interaction potential in terms of adiabatic radial components provides a description of the mechanism of the resonant trapping