Infrared spectroscopy allows access to the vibrational levels of molecules and thus permits the study of intermediates formed during optically triggered events. This research concerns the development of high repetition rate infrared spectroscopy aimed at studying protein dynamics via the vibrational spectra of the intermediate states. The thrust of this effort is the design of an optical parametric generator/amplifier system using silver thiogallate and gallium selenide crystals. This design, which is now being implemented, is enabling the acquisition of transient infrared spectra over the range 500 to 3000 cm-1. The system is using KTP and BBO OPA's to fill in the region from 3000 to 10,000 cm-1. This laser system is capable of generating extremely short pulses of visible (20fs) and infrared (40fs) radiation. In addition, we have coupled a 32 element MCT multiplexed detector array into the infrared probe generating system. With this system we have the capability of obtaining spectral measurements of coherent infrared signals. This allows for spectral resolution of infrared photon echoes, providing detailed information of vibrational energy flow within peptide and protein moieties. In total, we are developing pump/probe, transient grating, photon echo and heterodyned photon echo methods as part of the thrust in ultrafast infrared spectroscopy for proteins.
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