Search

Abstract: Angle-resolved ion yield (ARIY) spectroscopy has been carried out on high-temperature N2O molecules. From spectra recorded at 300K (room temperature) and at 700K, symmetry-resolved absorption profiles of the N 1s−1 3π and O 1s−1 3π resonances have been extracted from molecules in the vibrational ground state and in bending-vibration excited states. The spectra show dramatic differences, and the Renner–Teller effect becomes more evident for the vibrationally excited molecules. [Copyright &y& Elsevier]

Abstract: The C K-shell photoelectron mainline of C2H2 molecules have been measured at photon energies 295–350eV. The gerade and ungerade symmetries of the core-ionized states, 1σ g and 1σ u, are resolved. Resonance enhancement is found only in the 1σ g photoionization cross-section and assigned to the shape resonance. The photoelectron asymmetry parameter takes a minimum value at the shape resonance energy. The shape resonance energy decreases with increase in the vibrational quantum number. No correlational shape resonance appears in the 1σ u photoionization channel, suggesting that the channel coupling is negligible. [Copyright &y& Elsevier]

Abstract: We report differential cross sections and optical oscillator strength determinations for the respective excitation of vibrational sub-levels of the A2Σ+, C2Π and D2Σ+ electronic states in NO by 100eV electrons. While the differential cross section measurements are original, the present optical oscillator strengths are compared where possible with earlier values. In particular, a detailed comparison is made with the dipole (e,e) spectroscopy data from Chan et al. [W.F. Chan, G. Cooper, C.E. Brion, Chem. Phys. 170 (1993) 111], with generally very good agreement being found. [Copyright &y& Elsevier]

Abstract: Electron impact vibrational excitation cross sections are presented for carbonyl fluoride (F2CO). Measurements have been done for two of the six fundamental modes; the Cing and the Fh name="sbnd" />F symmetric vibrational modes. In the comparison of the vibrational Cing mode in F2CO with those in H2CO and CO molecules, the resonance energy at 20eV in CO was observed shifted to 17eV in F2CO and to 16eV in H2CO, a phenomenon explained as due to the increasing Cngth, in the order CO

Highlights: [•] Electron energy loss spectroscopy. [•] Ab initio calculations. [•] Triplet states. [Copyright &y& Elsevier]

Abstract: Observations of Auger transitions to quasi-stable states of CO2+ subsequent to C 1s−1 and O 1s−1 ionizations of CO are presented along with the corresponding photoelectron spectra and calculations of the potential energy curves. The equilibrium distances R e, the vibrational energies ω, and the anharmoncities x ω, for the final states a1Σ+, b1Π, A3Σ+, and d1Σ+ are derived from fits to the spectra by assuming Morse potentials. A comparison of these Morse potentials with theoretical potential energy curves reveals excellent agreement in the Franck–Condon regions of the Auger transitions. The relative intensities for the observed C 1s−1 and O 1s−1 Auger transitions are also derived. [Copyright &y& Elsevier]

Abstract: Angle-resolved energetic-ion yield spectra have been measured in the O 1s excitation region of N2O. Franck–Condon analysis based on ab initio two-dimensional potential energy surfaces of the core-excited Rydberg states reproduces well the observed vibrational excitations specific to the individual Rydberg states. The irregular Rydberg behavior in the Σ-symmetry absorption spectrum is attributed the valence-Rydberg coupling in light of the second moment analysis. [Copyright &y& Elsevier]

Abstract: Resonant photoemission from the fluoromethane (CH3F) molecule has been measured with photon energies scanning through the resonance in which a C or F1s electron is promoted to the lowest unoccupied molecular orbital . The spectator Auger band with the lowest binding energy of ∼27 eV is tentatively assigned to 2e−26a1. The energy-resolved electron–ion coincidence experiments revealed that this state produces predominantly ions both for C1s and F1s excitations, providing evidence that the spectator Auger decay to this state takes place within the molecular regime, where the valence electrons are delocalized over the entire molecule. [Copyright &y& Elsevier]

Total cross-sections (TCSs) for electron and positron scattering from C3H4 isomers (allene and propyne) were measured using the linear transmission method in the range of 0.8–600 eV for electrons and 0.7–600 eV for positrons. Elastic cross-sections for electron scattering were also measured by a crossed-beam experiment in the range of 2–100 eV. Sharp resonance-like peaks were observed in the electron TCSs for propyne around 3.6 and 8 eV, and 2.5 and 11 eV for allene. The positron TCSs for these molecules were found to be smaller and much smoother than the electron TCSs. Clear differences in resonance positions and magnitudes between the two isomers can be viewed as an isomer effect. [Copyright &y& Elsevier]