Laboratoire Francis PERRIN
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Fluorescence upconversion

A particular setup allows the recording of time-resolved fluorescence kinetics and spectra on the femtosecond timescale. This facility is dedicated to the study of time-resolved fluorescence spectra of molecules in the condensed phase.

The setup is based on the fluorescence upconversion technique. It uses a conventional Ti:S oscillator which produces ~100 femtosecond pulses at 800 nm which are subsequently frequency-doubled or -tripled to  400 or 267 nm used for excitation (pump pulse). The fluorescence emitted is collected and focused by reflective optics into a non-linear crystal together with the 800 nm gate pulse. The sum-frequency light is sent through a spectrometer to a photomultiplier and analysed as a function of the variable pump-probe delay.

Fluorescence in the spectral range from 300 to 800 nm can be recorded with an apparatus function of about 200 fs fwhm for 400 nm excitation and about 350 fs fwhm for 267 nm excitation. The time-resolution can be greatly reduced after deconvolution of data.