Broad-band fluorescence upconversion for femtosecond spectroscopy

Abstract

With near-infrared gating and improved light collection geometry, the entire fluorescence band can be upconverted in a broad range of 10 000 cm−1 without readjusting optical elements, thus allowing measurements with a single pump-gate scan. Monitoring of the pump-induced white light continuum provides for the time correction of the up-converted fluorescence spectra. The overall time resolution is then limited by the pump-gate cross correlation. The technique is illustrated with the femtosecond evolution of fluorescence from two molecular probes in solution.