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Femtosecond spectrally dispersed three‐pulse four‐wave mixing: the role of sequence and chirp in controlling intramolecular dynamics
Author(s) -
Lozovoy Vadim V.,
Grimberg Bruna I.,
Brown Emily J.,
Pastirk Igor,
Dantus Marcos
Publication year - 2000
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/(sici)1097-4555(200001/02)31:1/2<41::aid-jrs505>3.0.co;2-p
Subject(s) - chirp , femtosecond , coherence (philosophical gambling strategy) , excited state , four wave mixing , intramolecular force , raman spectroscopy , population , excitation , laser , degenerate energy levels , chemistry , atomic physics , physics , optics , molecular physics , nonlinear optics , quantum mechanics , demography , sociology
The roles of pulse sequence and pulse chirp were explored using femtosecond three‐pulse four‐wave mixing (FWM). The experiments were carried out on gas‐phase I 2 and the degenerate laser pulses are resonant with the transition between the X ( 1 Σ g +) ground and B ( 3 Π 0 u +) excited electronic states. Impulsive excitation leads to the observation of vibrational coherence in the ground and the excited states. Control over the observed population and vibrational coherence is achieved by using specific pulse sequences. Using chirped pulses results in changes in vibrational coherence. When the FWM signal is spectrally dispersed, the two‐dimensional data (wavelength and time delay) provide important spectroscopic information about the intramolecular dynamics of both electronic states. This information is not typically available in time or spectrally integrated measurements. A theoretical foundation for these observations based on the density matrix formalism is briefly discussed. Copyright © 2000 John Wiley & Sons, Ltd.