Subpicosecond Raman Spectrometer
SUBPICOSECOND RAMAN SPECTROMETER FOR TIME-RESOLVED STUDIES OF HEME PROTEINS
Sergei G. Kruglik and Michel Negrerie
We built a pump-probe Raman spectrometer based on a femtosecond Ti:Sapphire laser, an optical parametric generator and two optical parametric amplifiers for time-resolved studies of structural dynamics in heme proteins. The system provides a 100-fs pump pulse tunable in the range 500-600 nm and a transform-limited sub-picosecond probe pulse tunable in the range 390-450 nm. The spectrometer has spectral (25 cm-1) and temporal (~0.7 ps) resolutions which constitute an effective compromise for identifying transient heme protein species and for following their structural evolution by spontaneous Raman scattering in the time range 0.5 ps - 2 ns. This apparatus is applied to time-resolved studies of a broad range of heme proteins, monitoring the primary dynamics of photoinduced heme coordination state and structural changes, its interaction with protein side-chains and diatomic gaseous ligands, as well as heme vibrational cooling.