Rotational and vibrational effects in the E 1Sigma + g-X 1Sigma + g two-photon transitions of H2, HD, and D2
Abstract
A theoretical study is reported for the dependence of the E, F 1Σ+g-X 1Σ+g (vE=0, vX) Q-branch two-photon transitions on the initial vibrational and rotational quantum numbers vX and J for H2, HD, and D2. The magnitude of the two-photon transition moment ‖Mfo‖ increases with vX between 0 and 2, then decreases rapidly at higher vX. This behavior is ascribed to (constructive and destructive) interference effects in the two-photon transition, which vary with the nodal behavior of the initial-state vibrational wave function. The J dependence of ‖Mfo‖ is most strongly affected by the changes in vibrational wave functions caused by centrifugal distortion of the vibrational potentials. At low to intermediate J, the Franck-Condon overlap improves, resulting in a slow, monotonic increase of ‖Mfo‖ with J. At higher J, resonant tunneling between the inner and outer wells of the E, F state introduces sharp variations in the ‖Mfo‖ structure. Near the top of the barrier, nonresonant tunneling in the E-state vibrational wave function causes a general decrease in ‖Mfo‖ with J.
- Publication:
-
Journal of Chemical Physics
- Pub Date:
- July 1991
- DOI:
- 10.1063/1.461477
- Bibcode:
- 1991JChPh..95..205H
- Keywords:
-
- Deuterium;
- Hydrogen;
- Multiphoton Absorption;
- Rotational Spectra;
- Vibrational Spectra;
- Chemical Reactions;
- Electron Tunneling;
- Franck-Condon Principle;
- High Temperature Plasmas;
- Photoionization;
- Quantum Numbers;
- Atomic and Molecular Physics