Photoionization studies of the diatomic heteronuclear rare gas molecules XeKr, XeAr, and KrAr
The photoionization efficiency curves of the heteronuclear rare gas van der Waals molecules XeKr, XeAr, and KrAr were obtained with the molecular beam technique in the wavelength range from 790 to 1065 A (11.64--15.69 eV). The ionization potentials were found to be 11.757 +- 0.017 eV for XeKr, 11.985 +- 0.017 eV for XeAr, and 13.425 +- 0.020 eV for KrAr. From the known dissociation energies of the ground state XeKr, XeAr, and KrAr van der Waals molecules as determined by low energy molecular beam elastic scattering experiments, the binding energies for the ground state of the heteronuclear rare gas molecular ions were deduced to be 0.37 +- 0.02 eV for XeKr/sup +/, 0.14 +- 0.02 eV for XeAr/sup +/, and 0.59 +- 0.02 eV for KrAr/sup +/. The photoion spectra of the heteronuclear rare gas dimers R/sub 1/R/sub 2/ exhibit prominent autoionization structure, which is found to correlate very well with the excited molecular Rydberg states R/sub 1/*R/sub 2/ and R/sub 1/R/sub 2/* formed by the interaction of a normal ground state rare gas atom R/sub 1/ (or R/sub 2/) and an excited atom R/sub 2/* (or R/sub 1/*), in the n'p/sup 5/(/sup 2/P/sub 1///sub 2//sub ,//sub 3///sub 2/) ns (nd) configuration (where n'=3 for Ar, n'=4 for Kr, and n'=5 for Xe). The excitation of XeKr, XeAr, and KrAr is found to obey the parity selection rule ..delta..l= +- 1, in agreement with previous experimental observations in the photoionization studies of Kr/sub 2/ and Ar/sub 2/. The Rydberg series 5p/sup 2/(/sup 2/P/sub 1///sub 2/) ns (nd) for Xe, and 4p/sup 5/(/sup 2/P/sub 1///sub 2/) ns (nd) for Kr, were red shifted with respect to the positions in the photoionization efficiency curves of Xe and Kr. This allows one to calculate the potential energy for the excited molecular Rydberg state at a distance which corresponds to the equilibrium interatomic distance of the ground state van der Waals molecule. For Xe(5p/sup 5/(/sup 2/P/sub 1///sub 2/) ns (nd))+Ar(/sup 1/S/sub 0/) one obtains 0.06 eV and for Xe(/sup 1/S/sub 0/)+Kr(4p/sup 5/(/sup 2/P/sub 1///sub 2/) ns (nd)) 0.10 eV.
- Research Organization:
- Materials and Molecular Research Division, Lawrence Berkeley Laboratory and Department of Chemistry, University of California, Berkeley, California 94720
- OSTI ID:
- 7313187
- Journal Information:
- J. Chem. Phys.; (United States), Vol. 66:12
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
ARGON COMPOUNDS
IONIZATION POTENTIAL
PHOTOIONIZATION
KRYPTON COMPOUNDS
XENON COMPOUNDS
BINDING ENERGY
MOLECULAR BEAMS
VAN DER WAALS FORCES
BEAMS
ENERGY
IONIZATION
RARE GAS COMPOUNDS
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