DYNAMICS OF LOCAL SUBSTRUCTURES IN WATER OBSERVED BY ULTRAFAST INFRARED HOLE-BURNING

Transient hole burning in the OH-stretching region of HDO dissolved in D2O is investigated by two-color pump-probe spectroscopy in the tempe rature range 273-343 K. Spectral holes are observed with widths of 45 cm(-1) and a lifetime of approximate to 1 ps. The total OH band in the transient spectrum may be decomposed into three major constituents wi th different spectral and dynamical properties that are traced over th e full temperature range. From the measured cross relaxation among the spectral components a structural relaxation time of 1.5 +/- 0.5 ps (2 73 K) to 0.8 +/- 0.4 ps (343 K) is inferred.