Edward Pollack Memorial Lecture

Seeking Ways to Measure Atomic Dynamics in Real Time

Professor C. Lew Cocke
James R. Macdonald Laboratory
Physics Department
Kansas State University

Although it is straightforward to visualize and calculate the time-dependent motion of atoms in molecules and electrons in atoms, making experimental movies of this motion is quite a different matter. I will discuss some momentum-imaging experiments which yield experimental information on the timing of rearrangements in light molecules. If the transient state of the system is initiated using a single collisional pulse, an intrinsic clock must be used. For example, the diffraction of electrons ejected from the K-shell of an atomic constituent of the molecule takes a "picture" of the molecule, and the correlation between the momentum vector of the photoelectron and the subsequent fragmentation pattern can be used to estimate the time scale for the latter process. If the transient state is created with a short laser pulse, an external clock (pump-probe) with a resolution of a few fs is possible. Even shorter times can be observed by using in situ electron scattering from the molecular ion. Examples from double ionization of hydrogen and other light molecules by short laser pulses will be discussed.

Monday, April 17, 2006
Gant Science Complex
Physics Department
Room P38

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