Femtosecond CARS study of the intramolecular vibrational energy transfer in the electronic ground state of polymers

Summary form only given. The control of chemical reactions is one of the major goals of modern chemistry. In order to selectively break molecular bonds one has to consider the intramolecular vibrational energy redistribution (IVR) process in poly-atomic molecules. IVR usually makes it impossible to focus the laser energy in a certain bond of such molecules. The time scale of IVR is in the order of picosecond. With ultrashort laser pulses the phenomenon of the intramolecular-energy redistribution has been investigated in real time. Coherent Raman scattering on the time scale of less than 100 fs has been applied to liquid or gas phase samples to investigate the vibrational dynamics in their electronic ground or excited states. In the following, we will present results obtained for polymers of diacetylenes (PDBs). The investigations were performed on partly poly merited single crystals of PDAs symmetrically substituted with (2,4-hexa-diylyene-dip-fluoro-benzene sulfonate). The synchronous pump and Stokes pulses prepare a wave packet composed of several modes in the electronic ground state.