Rotationally resolved (1 + 1′), resonance-enhanced, two-photon ionization spectra of the C 0+u ← X 0+g transition of several isotopomers of Xe2 have been recorded. Rotational constants have been determined for the v′ = 1426 levels of the C 0+u Rydberg state and the v′′ = 0 and 1 levels of the X 0+g ground state, and band origins have been determined with an absolute accuracy of 0.015 cm1 for the transitions to the v′ = 1426 levels of the C 0+u state of the 129Xe2, 129Xe132Xe, and 131Xe136Xe isotopomers. The equilibrium internuclear separation of the X 0+g ground state (Re = 4.3773(49) Å) was determined from the rotational constants of the v′′ = 0 and 1 levels. The analysis of the isotopic shifts of the band origins enabled the confirmation of the absolute numbering of the vibrational levels of the C 0+u state determined by Lipson et al. (R.H. Lipson, P.E. Larocque, and B.P. Stoicheff. J. Chem. Phys. 82, 4470 (1985)). A semiempirical interaction potential for the X 0+g ground state was derived in a nonlinear fitting procedure using the present spectroscopic results, the positions of the v′′ = 29 levels determined by Freeman et al. (D.E. Freeman, K. Yoshino, and Y. Tanaka. J. Chem. Phys. 61, 4880 (1974)) and experimental values for the second virial coefficient. The interaction potential is similar to previous semiempirical potentials but the dissociation energy (De = (196.1 ± 1.1) cm1) differs from the value of 183.1 cm1 determined in the latest ab initio calculation (P. Slavíček, R. Kalus, P. Paka, I. Odvárková, P. Hobza, and A. Malijevský. J. Chem. Phys. 119, 2102 (2003)). Key words: high-resolution vacuum ultraviolet laser spectroscopy, rare gas dimers and their cations, photoionisation, Xe2, rotationally resolved electronic spectrum.
Determination of radiative lifetimes of excited states in neutral gold using time-resolved vacuum-ultraviolet laser spectroscopy
