Solution dynamics by line shape analysis, resonance light scattering and femtosecond four-wave mixing

Erik T.J. Nibbering, Koos Duppen, Douwe A. Wiersma

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Abstract

The results of line shape analysis, resonance light scattering and femtosecond four-wave mixing measurements are reported on several organic molecules in solution. It is shown that a Brownian oscillator model for line broadening provides a full description for the optical dynamics in aprotic solutions. The dynamics of all systems studied is found to occur in the intermediate modulation regime, where the amplitude Δ and inverse correlation time Λ of the Brownian oscillator are about equal: Δ/Λ ≈ 1. Isotopic substitution of either probe or solvent is shown to have no effect on the dynamics, from which it is concluded that the vibrational force field plays a minor role in determining the line shape. Four-wave mixing experiments with chirped femtosecond pulses yield intense coherent Raman scattering signals due to ground and excited-state vibrational coherences which are very effectively driven by the two instantaneous light fields whose frequency difference matches exactly a vibrational mode. It is shown that the “chirped” four-wave mixing signal near zero delay time only mimics the two-pulse photon echo if the system dynamics fall in the fast modulation limit: Δ/Λ « 1. Otherwise this signal is damped not only by dephasing but also by solvation dynamics.
Original languageEnglish
Pages (from-to)347-370
Number of pages24
JournalJournal of photochemistry and photobiology a-Chemistry
Volume62
Issue number3
DOIs
Publication statusPublished - 15-Jan-1992
Event15TH INTERNATIONAL CONF ON PHOTOCHEMISTRY - , France
Duration: 28-Jul-19912-Aug-1991

Keywords

  • INTERMEDIATE STATE INTERACTION
  • ORDER OPTICAL PROCESSES
  • RAMAN EXCITATION PROFILES
  • FAST RELAXATION PROCESSES
  • PUMP-PROBE SPECTROSCOPY
  • NON-MARKOVIAN THEORY
  • CONDENSED PHASES
  • POLYATOMIC-MOLECULES
  • STOCHASTIC-MODELS
  • PHOTON-ECHOES

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