On the limitations of adiabatic population transfer between molecular electronic states induced by intense femtosecond laser pulses

Abstract

The possibility to perform a stimulated Raman adiabatic passage process in molecules on the ultrafast time scale is investigated theoretically. Motivated by recent experiments, the mid R:B<--mid R:X electronic transitions in molecular iodine are studied as a prototype example with the goal to selectively induce a population transfer employing two intense and time-delayed ultrashort laser pulses and different coupling schemes. For the purpose of interpretation, the coupled multilevel vibronic problem is reduced to a quasi-three-level system by averaging over the vibrational degree of freedom. It is shown that the vibrational dynamics becomes essential at high field intensities. Considering a 2-dimensional parameter space (intensity and delay time of the femtosecond laser pulses), a strong-field control landscape is constructed.

Enhancing strong-field-induced molecular vibration with femtosecond pulse shaping

“…In the second case (previously studied in Ref. [28,29]), the efficiency of the transfer can reach up to a few percent, i.e. slightly higher than that in the far off-resonance arrangement; however, the dependance on the laser parameters remains erratic.…”

“…Here, the efficiencies observed in our calculations are substantially lower than those reported in Refs. [28,29]. In our calculation, the target population transfer into v f is hindered by one-photon coupling to the excited electronic state at the pump fre- quency.…”

“…Finally, we compare the results of the off-resonance excitation regime, with the two resonant cases, where a single-photon electronic excitation from either v 0 (case 1, l p = 573 nm, l S = 800 nm) or v f (case 2, l p = 645 nm, l S = 800 nm) is energetically allowed. The choice of these wavelengths is based on our experimental settings and on the previous studies [28,29]. In both cases, one-photon coupling to the excited electronic state at the pump frequency significantly complicates the population dynamics.…”

“…Earlier works have demonstrated a number of successful implementations of adiabatic transfer in twoand three-level systems driven by resonant laser radiation [23][24][25][26][27]. Previous studies questioned the utility of AP in multi-level molecular systems interacting with strong femtosecond pulses [28,29]. In this work we put to test the techniques of two-photon rapid adiabatic passage (RAP [30,31]), stimulated rapid adiabatic passage (STIRAP [23]) and "piecewise AP" [32,33].…”

Bichromatically driven double well: Parametric perspective of the strong field control landscape reveals the influence of chaotic states

“…Persistent theoretical and experimental efforts have led to the formulation of several ingenious control schemes 1,2,3,4 for both atomic and molecular systems. Recently researchers have been interested in determining the "control landscape" for specific systems 5,6,7,8,9,10,11,12,13 . The motivation for undertaking such extensive studies is atleast twofold.…”