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MO: Molekülphysik
MO 12: Poster I
MO 12.7: Poster
Tuesday, March 23, 2004, 14:00–16:00, Schellingstr. 3
Femtosecond Spectroscopy of Chlorine Molecules embedded in Solid Argon — •MIZUHO FUSHITANI, MATIAS BARGHEER, MARKUS GÜHR, and NIKOLAUS SCHWENTNER — Institut für Experimentalphysik, FU Berlin, Arnimallee 14, 14195, Germany
Ultrafast dynamics of chlorine molecules(Cl2) embedded in solid Argon(Ar) is studied by using fs pump-probe spectroscopy. A wavepacket of Cl2 was created on the inner limb of the B(3Π 0+u) and/or C(1Π 1u) electronic excited potentials by a pump pulse and the subsequent relaxation was monitored by a probe pulse which further excites the wavepacket to the ion-pair manifold. Due to the anharmonicity of the molecular potential, the wavepacket gets dispersed with time. The dispersion, however, can be precompensated by an appropriate chirped pulse. In this study, negatively chirped pulses were used to examine the wavepacket focusing of Cl2. The energy relaxation rate of a wavepacket at different vibrational energy levels in the B state was obtained by changing the wavelength of pump and probe pulses. The rate shows very different behaviors above or below the dissociation limit, indicating the different energy loss in the collision with the cage. We also carried out a phase-locked pulse pair experiment where the electronic coherence of molecules can be investigated. A pump pulse pair with a 0(π) phase shift excites more(less) number of molecules than a phase-unlocked pulse pair does, as long as molecules preserve the electronic coherence after each vibrational period. We observed the vibrational recurrence of Cl2 in solid Ar, which indicates that Cl2 keeps its electronic coherence for 250fs even if it is embedded in the solid where many-body electronic interactions take place.