Picosecond Raman Spectroscopy Using a Streak Camera

Abstract

A Raman measuring system using a streak camera has been constructed. This system consists of a picosecond pulsed laser, an astigmatism-corrected spectrograph, and a streak camera. It enables two-dimensional multichannel detection (time and frequency) of Raman scattering with time resolution as high as 10 ps (without deconvolution). The system was first applied to fluorescence background rejection. Raman spectra of benzene containing a trace amount of Rhodamine 640 were measured. The improvement factor of the Raman-to-fluorescence intensity ratio was estimated as 281, compared with the time-integrated cw measurement. Second, the system was used for picosecond time-resolved Raman spectroscopy. Nanosecond probing laser pulses were used with picosecond pumping. Raman scattering at each delay time was time-resolved and detected by the streak camera. Time-resolved Raman spectra of benzophenone at delay times ranging from −1.25 ns to 1.5 ns were obtained from one single measurement. These results indicate that, if properly designed and properly combined with a suitable optical setup, a streak camera has very high potential for Raman spectroscopy.