RAPID-SCAN PUMP-PROBE SPECTROSCOPY WITH HIGH TIME AND WAVE-NUMBER RESOLUTION - OPTICAL-KERR-EFFECT MEASUREMENTS OF NEAT LIQUIDS

A system for the rapid-scan (RS) acquisition of time-resolved nonlinea r spectroscopic signals, capable of femtosecond resolution over a rang e of tens of picoseconds, is presented. Operationally, the system is b ased on a magnetically driven, commercially available velocity transdu cer that continuously scans a probe delay line relative to a fixed del ay line while data are recorded on the fly and in real time. A simple calibration and data time-scale linearization are carried out and test ed on optical-heterodyne-detected optical-Kerr-effect measurements. Th ese results are compared with data acquired with a detection system th at is based on a stepped delay-line lock-in amplifier. It is found tha t the RS system is favorable in several areas of signal acquisition, i ncluding signal-to-noise ratio, acquisition time, spectral resolution in the Fourier-transformed data, and immunity to artifacts such as bas eline distortions.