Construction of picosecond time-resolved Raman spectrometers with near-infrared excitation


  • Presented as part of a commemorative issue for Wolfgang Kiefer on the occasion of his 65th birthday.


We have constructed two types of picosecond time-resolved Raman spectrometers with near-infrared excitation. One system is based on a step-scan Fourier transform (FT) interferometer equipped with a Ge detector, and the other system is based on a dispersive spectrometer equipped with an InGaAs array detector. For the former system with pulsed Raman excitation, we have developed a new method of signal processing. This method does not require synchronization among laser pulses for Raman excitation, the stepping of the step-scan interferometer, and the sampling of the analog-to-digital converter. In spite of large fluctuation in the probe-pulse energy, the ordinary FT-Raman spectra of samples in the ground electronic state can be obtained with satisfactory signal-to-noise ratios by the former system. By the latter system, picosecond transient Raman spectra have been obtained from the first excited singlet (S1) state of 9-phenylanthracene and the second excited singlet (S2) state of all-trans-β-carotene by using 388-nm light for photoexcitation and 1064-nm light for Raman excitation. Copyright © 2006 John Wiley & Sons, Ltd.