Abstract

In this work we report the result of a photoionization experiment in which photoelectron energy spectra were collected following 2+1 MPI of H₂ via the E,F states. The bound states studied include those at the bottom of the inner E-well (v_E,F=3), at the barrier of the double potential in the inside E-well (v_E,F=6) and its counterpart in the outer F-well (v_E,F=7), and above the barrier (v_E,F=9). The E,F state wavefunctions are not confined in one or the other potential well only. This leads to a dynamic competition between direct photoionization, autoionization and dissociation. In our experiment the photoelectrons show strong non-Franck-Condon vibrational distribution. Some of the high vibrational states of ${\text{H}}_2^{+}$ are so largely enhanced that they dominate the electron spectra, for examples, the v⁺=13 in v_E,F=6, and the v⁺=14, 16 in v_E,F=9; the "Franck-Condon picture" is even more distorted when a mainly F-state is excited as in v_E,F=7.

SUMMARY In this work we report the result of a photoionization experiment in which photoelectron energy spectra were collected following 2+1 MPI of H₂ via the E,F states. The bound states studied include those at the bottom of the inner E-well (v_E,F=3), at the barrier of the double potential in the inside E-well (v_E,F=6) and its counterpart in the outer F-well (v_e,f=7), and above the barrier (v_e,f=9). The E,F state wavefunctions are not confined in one or the other potential well only. This leads to a dynamic competition between direct photoionization, autoionization and dissociation. In our experiment the photoelectrons show strong non-Franck-Condon vibrational distribution. Some of the high vibrational states of ${\text{H}}_2^{+}$ are so largely enhanced that they dominate the electron spectra, for examples, the v⁺=13 in v_e,f=6, and the v⁺=14, 16 in v_e,f=9; the "Franck-Condon picture" is even more distorted when a mainly F-state is excited as in v_e,f=7. The experient is performed with a YAG-PDL-WEX pulse laser system and a high-presure H2 Raman cell. Photoelectrons are collected in a state-of-the art high resolution TOF electron spectrometer which uses permanent magnets in the magnetic bottle design. We compare the experimental results with a theoretical calculation of cross sections which includes contributions from direct photoionization and autoionization using the nonlocal complex potential method.

© 1988 Optical Society of America