Femtosecond far-infrared pump-probe spectroscopy: A new tool for studying low-frequency vibrational dynamics in molecular condensed phases
1997; Elsevier BV; Volume: 274; Issue: 4 Linguagem: Inglês
10.1016/s0009-2614(97)00705-7
ISSN1873-4448
AutoresGilad Haran, Weidong Sun, Klaas Wynne, Robin M. Hochstrasser,
Tópico(s)Spectroscopy and Laser Applications
ResumoLow-frequency (terahertz) motions that play an important part in reactive processes in condensed phases are directly probed, following an optical excitation. A voltage-biased semiconductor wafer, excited with a 70 femtosecond laser pulse, is employed as a source for intense terahertz pulses, which are used as the probe arm of a pump-probe experiment. Difficulties in using terahertz probe pulses are discussed. We then demonstrate the method with two examples. In the first, a terahertz signal is shown to follow the solvent response to charge transfer in betaine. In the second example, relaxation of sapphire lattice phonons, excited impulsively by a 405 nm pulse, is observed.
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