Energetic laser pulses (300 ?J- 2 mJ) are being utilized to excite absorptive dyes in solution. These dyes act as heat transducers, taking the optical energy and converting it to thermal energy. This thermal energy diffuses throughout the bulk solvent in ca. 100 ps, raising the temperature of the solvent on the order of 8-100 C. We are utilizing and exploring further optical parametric methods of generating the pulses that can be directly absorbed into the overtone bands of the solvent water (ca. 1.5-1.9 ?m). The temperature jump is being used to induce conformational changes associated with unfolding in proteins. Ultrafast infrared and visible probes have been developed to monitor the kinetics of these changes. Further modifications have been made to the system to allow observation of spectral changes on the ps to ms timescale. Other protein candidates are being considered, in particular those which undergo cold """"""""naturation"""""""" such that we may observe changes associated with the folding processes.
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