Ionization, dissociation, and level shifts ofH2+in a strong dc or low-frequency ac field

Complex-scaling generalized pseudospectral method for quasienergy resonance states in two-center systems: Application to the Floquet study of charge resonance enhanced multiphoton ionization of molecular ions in intense low-frequency laser fields

“…Also shown in Fig. 11 for comparison are the the cycleaveraged dc quasienergy widths of the 2p state ͑i.e., the average of the dc ionization rates over all instantaneous value of the ac-field strength during one optical cycle͒ obtained by Mulyukov et al,͓8͔. These ͑frequency-independent͒ dc quasienergy widths are significantly higher than those of the time-dependent results of Zuo and Bandrauk ͓6͔, although the peak heights of the dc rates are likely to be an overestimation.…”

Decay of a negative molecular ion in a constant electric field

“…Another interesting feature of the interaction of the ion with constant field F is the nonmonotonic dependence of width Γ -of the excited state on the internuclear spacing upon an increase in R. The physical origin of such a dependence is disput able, and three different hypotheses exist concerning this dependence [9,10,14]. In [9], the nonmonotonic dependence Γ -(R) is explained by charge resonance 1 existing between the ground state and the first excited state of (the wavefunctions of these states for F = 0 exhibit opposite symmetries relative to transposition of nuclei) and by the lowering of the barrier for tunnel ing from the excited state for certain values of R and F. Conversely, the nonmonotonic behavior of the width is explained in [10] by the involvement of intermediate resonances associated with highly excited levels of into tunneling of a particle through the barrier formed by the field of the two centers and the constant field.…”

“…Another interesting feature of the interaction of the ion with constant field F is the nonmonotonic dependence of width Γ -of the excited state on the internuclear spacing upon an increase in R. The physical origin of such a dependence is disput able, and three different hypotheses exist concerning this dependence [9,10,14]. In [9], the nonmonotonic dependence Γ -(R) is explained by charge resonance 1 existing between the ground state and the first excited state of (the wavefunctions of these states for F = 0 exhibit opposite symmetries relative to transposition of nuclei) and by the lowering of the barrier for tunnel ing from the excited state for certain values of R and F. Conversely, the nonmonotonic behavior of the width is explained in [10] by the involvement of intermediate resonances associated with highly excited levels of into tunneling of a particle through the barrier formed by the field of the two centers and the constant field. Finally, the nonmonotonic dependence of Γ -on R is attributed in [14] (based on analysis of the 2D model of the ion in field F parallel to R) to the interfer ence of two waves emerging during tunneling from the excited state; one of these waves is determined by direct tunneling, while the other is determined by tun neling with rescattering from the neighboring atomic center followed by the reflection from the barrier formed by field F. (It should be noted that this inter pretation is confirmed in our study by the results of an exactly solvable 3D model.)…”

“…Such a dependence of energy on the field strength and internuclear separation is due to localization of an electron at one of the centers, which leads to the emer gence of a dipole moment ± R/2 interacting with the field [10,11,13]. Another interesting feature of the interaction of the ion with constant field F is the nonmonotonic dependence of width Γ -of the excited state on the internuclear spacing upon an increase in R. The physical origin of such a dependence is disput able, and three different hypotheses exist concerning this dependence [9,10,14].…”

“…The shifts and widths of the elec tron molecular terms in a constant field were calcu lated numerically in [9] for the simplest molecule ( ion) by direct numerical integration of the Schrödinger equation. Analogous but more detailed numerical analysis was carried out in [10,11] (see also [12]). These numerical results confirmed the linear field dependence of the position of the ground (⑀ + ) and first excited (⑀ -) states of with increasing R, which was predicted earlier in [13]:…”