Following dynamic nuclear wave packets in N2,O2, and CO with few-cycle infrared pulses

Abstract

Abstract:We study the evolution of nuclear wave packets launched in molecular nitrogen, oxygen and carbon monoxide by intense 8fs infrared pulses.We use velocity map imaging to measure the momentum of the ion fragments when these wave packets are interrogated by a second such pulse after a variable time delay. Both quasi-bound and dissociative wave packets are observed. For the former, measurements of bound-state oscillations are used to identify the participating states and in some cases extract properties of the relevant potential energy surfaces. Vibrational structure is resolved in both energy and oscillation-frequency for the cations of oxygen and carbon monoxide, displaying the same quantum wave packet motion in both energy and time domains. In addition, vibrational structure is seen in the dication of carbon 2 monoxide in a situation where the energy resolution by itself is inadequate to resolve the structure.

Dissociation dynamics of diatomic molecules in intense laser fields: A scheme for the selection of relevant adiabatic potential curves

“…4). Comparison of the simulated vibrational periods, revival times, and QB frequencies for a number of electronic states with measured KER spectra [7] revealed the a 4 u state as the best match to the experimental oscillation period and QB frequencies. Table I shows a comparison of the calculated and measured parameters for each potential curve we tried in our calculations.…”

“…4(a) and 4(c)], with pump-probedelay-dependent measured KER data [5][6][7][12][13][14]20,21]. We obtained additional information for selecting electronic states that participate in the bound and dissociative nuclear motion of the molecular ion by comparing probability densities obtained from single-curve calculations with measured KER spectra as a function of the pump-probe delay (propagation time) and QB frequency [12][13][14].…”

“…Thus, state a 4 u appears to be the most relevant in the dissociative dynamics, which is also in agreement with the experimental findings in Refs. [7,20].…”

“…The extension of these investigations to heavier molecules is not straightforward, and the interpretation of experimental data is intricate due to the large number of molecular potential curves involved. By analyzing KER spectra from dissociated oxygen ions as a function of the time delay, we recently found that usually several intermediate electronic states of the molecular ion contribute to the same KER [5][6][7]. In Refs.…”

“…In Refs. [5,7] the dynamics of N 2 , O 2 , and CO molecules in intense laser pulses was studied using the Coulomb explosion (CE) imaging technique. In comparison with classical and quantum-mechanical simulations, transiently populated intermediate states for molecular ions in different charge states and associated dissociation pathways were identified.…”