CONSTRUCTION OF A TRANSFORM-LIMITED PICOSECOND TIME-RESOLVED RAMAN SPECTROMETER

A pump-probe picosecond time-resolved Raman spectrometer has been constructed using a dye laser synchronously pumped by a cw mode-locked Nd:YAG laser and a high repetition rate (2 kHz) dye amplifier pumped by the frequency doubled output from a cw Nd:YAG regenerative amplifier. Transform-limited picosecond pulses with 3.5 cm-1 wave number width and 3.2 ps temporal width are obtained at the wavelength of 588 nm. The second harmonic of these pulses is generated at 294 nm and is used for pumping, while the remaining visible pulses are used for probing. resonance Raman scattering. The cross-correlation time between the pump and probe pulses is 4.1 ps. The temporal profile of the laser pulse is found to be very close to the sech2 shape. The wave number resolution of the system is estimated to be 3.5 cm-1 according to the Tailor criterion. The time resolution is estimated to be 2.2 ps using a criterion newly proposed in the present paper. Time-resolved Raman spectra of S1 trans-stilbene and S1 p-terphenyl are presented to demonstrate the capability of the constructed spectrometer.