Chapitre D'ouvrage Année : 2001

Investigations of Femtosecond Chemical Reactivity by means of Fluorescence Upconversion

Résumé

Fluorescence-emission spectroscopy is a powerful tool for the study of the reactivity of chemical and biological systems. As the fluorescence spectrum and the fluorescence quantum yield, the fluorescence lifetime of chromophors depend on their microenvironment. During the past thirty years, the rapid development of tunable laser sources has opened large opportunities for the study of the deactivation of the fluorescent excited states of molecules in the nano-, pico- and femtosecond time range. When analysing the fluorescence intensity as a function of time, the pre-exponential factors and time constants are determined after a careful deconvolution through the use of a computer-based algorithm. Several techniques are used, phase modulation spectroscopy with a sinusoidally modulated argon-ion or dye-laser pump source on a time scale comparable to the decay times of interest, time-correlated single photon counting with pump pulses (nanosecond pulsed flashlamps or picosecond laser pulses) short compared to the fluorescence decay time, ultra-fast streak cameras designed for the conversion of the time dependence of light emission I(t) into the distance dependence of electron impact on a phosphor screen I(x) [1]. Although most of the fluorescence studies deal with the UV-visible spectral domain, time resolved measurements are now performed in the near-IR due to advances in IR instrumentation [2]. For the measurement of fast decays in the 1-100 ps range, time-correlated single photon counting can be used in conjunction with mode-locked and cavity-dumped dye lasers and recently with mode-locked Ti:sapphire lasers. However, the time resolution of those techniques remains limited.

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Dates et versions

hal-00136519 , version 1 (14-03-2007)

Identifiants

  • HAL Id : hal-00136519 , version 1

Citer

J.-C. Mialocq, T. Gustavsson. Investigations of Femtosecond Chemical Reactivity by means of Fluorescence Upconversion. New trends in fluorescence spectroscopy, Valeur, B. Brochon, J. C. Springer Verlag, pp.77, 2001. ⟨hal-00136519⟩
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