Alexander Chartrand

Photoelectron angular distributions from rotationally resolved autoionizing states of N2

The single-photon, photoelectron-photoion coincidence spectrum of N2 has been recorded at high (∼1.5 cm-1) resolution in the region between the N2+ X Σg2+, v+ = 0 and 1 ionization thresholds by using a double-imaging spectrometer and intense vacuum-ultraviolet light from the Synchrotron SOLEIL. This approach provides the relative photoionization cross section, the photoelectron energy distribution, and the photoelectron angular distribution as a function of photon energy. The region of interest contains autoionizing valence states, vibrationally autoionizing Rydberg states converging to vibrationally excited levels of the N2+ X Σg2+ ground state, and electronically autoionizing states converging to the N2+A2Π and B 2Σu+ states. The wavelength resolution is sufficient to resolve rotational structure in the autoionizing states, but the electron energy resolution is insufficient to resolve rotational structure in the photoion spectrum. A simplified approach based on multichannel quantum defect theory is used to predict the photoelectron angular distribution parameters, β, and the results are in reasonably good agreement with experiment.

Double resonance spectroscopy of the and states near the third dissociation threshold of H2

Double-resonance laser spectroscopy via the state was used to probe the energy region below the third dissociation limit of molecular hydrogen. Resonantly enhanced multi-photon ionization spectra were recorded by detecting ion production as a function of energy using a time-of-flight mass spectrometer. Energies and line widths for the v = 14–17 levels of the state of H2 are reported and compared to experimental data obtained by using VUV synchrotron light excitation (Dickenson et al 2010 J. Chem. Phys. 133 144317) and fully ab initio non-adiabatic calculations of state energies and line widths (Glass-Maujean et al 2012 Phys. Rev. A 86 052507). Several high vibrational levels of the state were also observed in this region. Term energies and rotational constants for the v = 67–69 vibrational levels are reported and compared to highly accurate ro-vibrational energy level predictions from fully ab initio non-adiabatic calculations of the first six levels of H2 (Wolniewicz et al 2006 J. Mol. Spectrosc. 238 118). While additional observed transitions can be assigned to other states, several unassigned features in the spectra highlight the need for a fully integrated theoretical treatment of dissociation and ionization to understand the complex pattern of highly vibrationally excited states expected in this region.

Double resonance spectroscopy of the

Double-resonance laser spectroscopy via the state was used to probe the energy region below the third dissociation limit of molecular hydrogen. Resonantly enhanced multi-photon ionization spectra were recorded by detecting ion production as a function of energy using a time-of-flight mass spectrometer. Energies and line widths for the v = 14–17 levels of the state of H2 are reported and compared to experimental data obtained by using VUV synchrotron light excitation (Dickenson et al 2010 J. Chem. Phys. 133 144317) and fully ab initio non-adiabatic calculations of state energies and line widths (Glass-Maujean et al 2012 Phys. Rev. A 86 052507). Several high vibrational levels of the state were also observed in this region. Term energies and rotational constants for the v = 67–69 vibrational levels are reported and compared to highly accurate ro-vibrational energy level predictions from fully ab initio non-adiabatic calculations of the first six levels of H2 (Wolniewicz et al 2006 J. Mol. Spectrosc. 238 118). While additional observed transitions can be assigned to other states, several unassigned features in the spectra highlight the need for a fully integrated theoretical treatment of dissociation and ionization to understand the complex pattern of highly vibrationally excited states expected in this region.

{\rm D} {}^1 \Pi _{\rm u}^+

Double-resonance laser spectroscopy via the state was used to probe the energy region below the third dissociation limit of molecular hydrogen. Resonantly enhanced multi-photon ionization spectra were recorded by detecting ion production as a function of energy using a time-of-flight mass spectrometer. Energies and line widths for the v = 14–17 levels of the state of H2 are reported and compared to experimental data obtained by using VUV synchrotron light excitation (Dickenson et al 2010 J. Chem. Phys. 133 144317) and fully ab initio non-adiabatic calculations of state energies and line widths (Glass-Maujean et al 2012 Phys. Rev. A 86 052507). Several high vibrational levels of the state were also observed in this region. Term energies and rotational constants for the v = 67–69 vibrational levels are reported and compared to highly accurate ro-vibrational energy level predictions from fully ab initio non-adiabatic calculations of the first six levels of H2 (Wolniewicz et al 2006 J. Mol. Spectrosc. 238 118). While additional observed transitions can be assigned to other states, several unassigned features in the spectra highlight the need for a fully integrated theoretical treatment of dissociation and ionization to understand the complex pattern of highly vibrationally excited states expected in this region.