Construction of a Picosecond Time-Resolved IR Dip Spectrometer for Studying Structures and Dynamics of Solvated Clusters

We have constructed a picosecond time-resolved IR dip spectrometer having a frequency resolution of < 20 cm^-1 and an instrument response time of 25 ps. In this system, the second harmonic of the idler wave from the OPA pumped at 800 nm and the remaining light from a regenerative amplifier (< 2.5 mJ/pulse) were differentially mixed in a KTA crystal to generate tunable high-power IR light (2750-4000 cm^-1; > 60 (mu)J). The picosecond time-resolved IR dip spectra of phenol(H2O)1 and carbazole-(H2O)1 are presented to demonstrate the capability of the constructed system. The spectral changes show clear vibrational structures of not only S0, but also S1 in the 2800-3800 cm^-1 energy region. The system performance is also discussed.