Picosecond fluorescence depletion spectroscopy. I. Theory and apparatus

Abstract

This paper describes the experimental implementation and theory of a new technique for the time resolved study of intramolecular vibrational redistribution: time resolved fluorescence depletion (TRFD). Picosecond time resolution is obtained by using two pulses of identical wavelength and duration to create and then stimulate emission from a vibrational state in S1. Spontaneous emission intensity is measured as a function of delay between pulses. By monitoring the efficiency with which the second pulse stimulates emission, the evolution of the initial optically prepared state can be followed. A description of the apparatus built for these experiments is also presented.