Femtosecond Coherent Raman Spectroscopy

摘要

Femtosecond time-resolved CARS spectroscopy is applied in order to prepare and monitor coherent states of different samples mainly in its electronic ground but also excited states. The time evolution prepared by such methods give information on the dynamics of molecular vibrations. In a first example, the fs CARS transients of iodine are investigated. Depending on the timing of the laser pulses different dynamics are reflected in the transient CARS signal. Second, we report on selective excitation of the vibrational modes in the electronic ground state of polymers of diacetylene by means of a femtosecond time-resolved CARS scheme. Control is achieved by varying the timing and the phase shape (chirp) of the exciting laser pulses. Finally the electronic ground state dynamics of biologically relevant porphyrine molecules are studied with transient CARS spectroscopy.