Effect of Nonresonant Frequencies on the Enhancement of Quantum Beat Amplitudes in Rovibrational States of Li2: The Role of State Spacing

Published

December 1, 2002

Author(s)

E Mirowski, H U. Stauffer, J B. Ballard, B Zhang, C L. Hetherington, S R. Leone

Abstract

Optical phase manipulation of nonresonant frequencies is investigated as a method of achieving optimal population transfer during a resonant impulsive stimulated Raman scattering (RISRS) process between two electronic states in Li₂. State selective excitation of an initial single rovibrational state by a tunable cw laser, followed by creation of a Raman pumped wave packet with an ultrafast pulse initial single rovibrational state by a tunable cw laser, followed by creation of a Raman pumped wave packet with an ultrafast pulse centered at 800 nm provides quantitative comparison of two quantum beat amplitudes as a function of applied phases in the ultrafast pulse. The amplitudes are explored for two pairs of states, one with wide state spacing (50.14 cm^-1) and one with narrow spacing (16.6 cm^-1). The first pair of states involves the initial A(vA=11,J_A=28) states beating with the newly formed A(v_A = 11, J_A = 30) state. The second pair involves the beating of the initial A (v_A=11.J_A=8) and newly formed A (V_A=10) states. Several different phase masks are applied to the wave packet preparation pulse to enhance the population in the newly formed state of interest. One involves application of a -90 phase block to the nonresonant frequencies of the pulse that lie between the resonant transition frequencies. Another involves extending the phase modification to the nonresonant frequencies lying outside the two resonant transitions in blocks of steps equal to the state spacing. The population of the newly formed A(v_A=11,J_A=30) and A(V_A=11,J_A=10) states are demonstrated with the proper choice of phase relationships between pairs of frequencies throughout the laser pulse spectrum. In addition, the dependence of the state spacing on the extent to which nonresonant frequencies affect the population transferred in the RISRS process is demonstrated.

Citation

Journal of Chemical Physics

Volume

117

Issue

No. 24

Pub Type

Journals

Keywords

2-photon transition, femtosecond, quantum control, selectivity

Citation

Mirowski, E. , Stauffer, H. , Ballard, J. , Zhang, B. , Hetherington, C. and Leone, S. (2002), Effect of Nonresonant Frequencies on the Enhancement of Quantum Beat Amplitudes in Rovibrational States of Li₂: The Role of State Spacing, Journal of Chemical Physics (Accessed April 25, 2024)