We investigate the mechanism of enhanced ionization in the two electron molecule H2 subjected to an ultrashort, intense laser pulse by solving exactly the time-dependent Schrödinger equation for a one-dimensional model. Results of the simulation are analyzed by using the "field following" three adiabatic states that are adiabatically connected with the lowest three essential electronic states of H2 as a field changes. Ionization is enhanced when the excited ionic state H-H+ is most efficiently created from the covalent ground state HH in the level dynamics prior to ionization. An analytic expression for the ionic and covalent crossing condition is also obtained in terms of the three essential states and agrees well with the numerical results. As the internuclear distance R decreases, the population of the H-H+ created increases whereas the ionization rate from a pure H-H+ state decreases owing to the stronger attraction by the distant nucleus. As a result, the ionization is most enhanced at intermediate internuclear R (≈6) range where covalent and ionic configurations cross.
|Number of pages||10|
|Publication status||Published - 2001 Feb 1|
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics
- Industrial and Manufacturing Engineering