The FLUME (Fluorescence upconversion) platform is a special facility for obtaining time-resolved fluorescence spectra of condensed-phase molecules, enabling the study of molecular kinetics on the femtosecond scale.
The system is based on the fluorescence conversion technique. It uses a conventional Ti:S oscillator that produces ~100 femtosecond pulses at 800 nm, which are then doubled or tripled in frequency at 400 or 267 nm and used for initial excitation (pump pulse). The emitted fluorescence is collected and focused by reflective optics in a non-linear crystal with a second delayed probe pulse at 800 nm. The emitted fluorescence is transmitted by a spectrometer to a photomultiplier, then analyzed as a function of the variable delay between the pump and probe beams.
Fluorescence in the 300-800 nm spectral range can be recorded with a device function of ~200 fs fwhm, for a 400 nm excitation pulse, and ~350 fs fwhm for a 267 nm excitation. Time resolution can be considerably reduced after data deconvolution.
