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Colloquia

ics Colloquium
Friday, January 21, 2005
4:00 PM
Physics Building, Room 204
Note special time.
C. L. (Lew) Cocke [Host: Tom Gallagher]
Kansas State University
"Photon-ion Collisions and Molecular Clocks"
ABSTRACT:
The timing of molecular rearrangemnts can be followed in the time domain on a femtosecond scale by using momentum imaging techniques. Three examples will be discussed: First, the diffraction of electrons ejected from the k-shell of one of atomic constituents of the molecule takes a "picture" of the molecule, and the correlation between the momentum vector of the photoelectron and the subsequent fragmentation pattern is used to estimate the time delay which accompanies the latter process. Second, the kinetic energy release of proton pairs from the double ionizaton of hydrogen by fast laser pulses is timed using the 2.7 fs optical cycle as a clock. The mechanisms of rescattering, sequential and enhanced ionization are clearly identified in the momentum spectra. Pump probe experiments allow us to follow the simultaneous propagation of coherently launched wave packets in different exit channels. Third, the operation of rescattering double ionization in the case of nitrogen and oxygen molecules will be discussed. The use of rescattering to probe the structure of the outer orbitals in molecules will be demonstrated.

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