Impulsive control of ground surface dynamics of I 3 - in solution

Erez Gershgoren, J. Vala, R. Kosloff, S. Ruhman*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

50 Scopus citations

Abstract

Coherent control of I 3 - ground state dynamics in ethanol and acetonitrile solutions is demonstrated. The method is based on impulsive excitation creating a dynamic hole employing sub 30 fsec tunable UV laser pulses. The target of control was to increase the ratio of second to first harmonic spectral modulations of the symmetric stretching vibrational coherences. Methods demonstrated to achieve this target include altering pulse intensity when the excitation pulses are tuned to the maximum of the absorption peak, double excitation pulses separated by half a vibrational cycle, and tuning the pumping or probing pulses to a wavelength simultaneously resonant with both absorption bands of ground state I 3 -. Chirping the probing pulses further allows full mapping of the ground state coherence in phase space, pinpointing the position of the dynamic holes not only in coordinate space but also in momentum. A theoretical model reconstructs the results nearly quantitatively and provides insight into the mechanisms active in achieving the control aims. It further demonstrates how the fundamental suppression serves to precisely characterize the relaxation dynamics of weak spectral features such as higher harmonics of the symmetric stretching and the antisymmetric stretching fundamental. In particular, the ratio of dephasing rates of the first two harmonics (∼2.3) deviates considerably from the ratio of 4 predicted by Kubo line shape theory. Possible sources of this discrepancy based upon alternative dephasing models are discussed.

Original languageEnglish
Pages (from-to)5081-5095
Number of pages15
JournalJournal of Physical Chemistry A
Volume105
Issue number21
DOIs
StatePublished - 31 May 2001

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