A microsecond time-resolved infrared spectrometer has been constructed. It is based on a dispersive infrared spectrometer modified for fast gated detection with a boxcar integrator synchronized with the photoexcitation by a high-repetition-rate cw Q-switched Nd: YAG laser. Time-resolved infrared spectra of τ-form metal-free phthalocyanine (τ-H2Pc) fine particles have been obtained with a gate width of 0.5 μs. It is most probable that the triplet exciton of τ-H2Pc and its bimolecular decay process (triplet-triplet annihilation) have been observed.
Koichi Iwata, Chihiro Kato, and Hiro-o Hamaguchi, "Microsecond Time-Resolved Infrared Spectroscopy of a Thin Film of τ-Form Metal-Free Phthalocyanine Fine Particles," Appl. Spectrosc. 43, 16-19 (1989)