An International Research Journal

AJP

SSN : 0971 - 3093

Vol  12, No 1, January - March, 2003

Asian Journal of Physics                                                                                                             Vol. 12, No 1 (2003) 1-12


Dynamics by femtosecond time-resolved coherent anti Stokes Raman spectroscopy


M Schmitt, T Siebert, A S Grabtchikov, V Orlovich and W Kiefer

1Institut fur Physikalische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Fedral Republic of Germany

2B I Stepanov Institute of Physics, National Academy of Sciences of Belarus, Minsk, Belarus.

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Femtosecond time-resolved CARS spectroscopy is applied in order to prepare and monitor coherent states of different samples. The time evolution prepared by such methods gives information on the dynamics of molecular vibrations. In a first example the electronic ground state dynamics of biologically relevant porphyrin molecules are studied with transient CARS spectroscopy. 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 pulse . Finally the capability of the CARS process to interrogate individual normal modes  was utilized for exploring the influence of nuclear dynamics on the process of the S1/S0 internal conversion (IC) in β-carotene, by placing the CARS process in a pump-probe scheme, where it plays the role of a mode selective probe.

1 Introduction

 Elementary steps in chemical reactions involve the breaking and formation of molecular bonds. The time scale for these processes is of the order of 100fs.Therefore, femtosecond time resolved spectroscopy enables researchers

Total Refs: 65

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