Coherent polyatomic dynamics studied by femtosecond time-resolved photoelectron spectroscopy: Photodissociation of CS2

PHYS 371

Kenneth L Knappenberger Jr.,, Department of Chemistry, University of California, Berkeley, Lawrence Berkeley National Labs, Berkeley, CA 94720, Eliza Beth Lerch, College of Chemistry and Dept. of Physics, University of California Berkeley, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-1460, Patrick Wen, Univeristy of California, Berkeley, and Stephen R. Leone,, Departments of Chemistry and Physics, University of California at Berkeley / Lawrence Berkeley National Lab, 209 Gilman Hall, Department of Chemistry, Berkeley, CA 94720.
The dissociation dynamics of the 6s and 4d Rydberg states of carbon disulfide (CS2) are studied by time-resolved photoelectron spectroscopy. The CS2 is excited by two-photons of 266 nm and probed by one-photon at 800 nm. Both spin 1/2 and 3/2 cores of the excited Rydberg states are distinguished. The dissociation mechanism produces multiple product states, with the primary channel forming the excited CS(a3b) fragment. Multi-mode vibrational wavepackets are created and observed through recurrence interferences in the final state, and the composition is varied by tuning the excitation to particular resonances. Fourier transformation of the temporal response reveals the coherent population of several stretching and bending modes. The dynamics exhibit significant sensitivity to the electronic and vibrational states accessed in the pump step. Population of the bending mode results in an excited state lifetime of approximately 500 fs, as compared to a several picosecond lifetime observed for the electronic origins.

Poster Session
7:30 PM-10:00 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster

8:00 PM-10:00 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Sci-Mix

Division of Physical Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006