Ultrasensitive coherent Raman technique with picosecond lasers

Abstract

The use of picosecond, Q-switched lasers and advanced polarization schemes has led to the development of a coherent Raman technique with the sensitivity of coherent anti-Stokes Raman spectroscopy experiments but without the troublesome phase-matching requirements. Experiments in dilute solutions of benzene indicate a limit of sensitivity for the current apparatus of 2.5×10−4 M in two minutes of signal averaging over 150 cm−1. Possible applications to the in situ study of passive films and thin films on transparent media are discussed.