Photoionization dynamics

11 Photoelectron Angular Distribution, Photoion Alignment, and Spin Polarization. 595 

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At a fundamental level, it has been shown that PECD stems from interference between electric dipole operator matrix elements of adjacent continuum f values, and that consequently the chiral parameters depend on the sine rather than the cosine of the relative scattering phases. Generally, this provides a unique probe of the photoionization dynamics in chiral species. More than that, this sine dependence invests the hj parameter with a greatly enhanced response to small changes in scattering phase, and it is believed that this accounts for an extraordinary sensitivity to small conformational changes, or indeed to molecular substitutions, that have only a minimal impact on the other photoionization parameters. 

D. Shemesh and R. B. Gerber. Classical trajectory simulations of photoionization dynamics of tryptophan intramolecular energy flow, hydrogen-transfer processes and conformational transitions, J. Phys. Chem. A, 110 8401-8408 (2006). 

The PFI spectrum of CO illustrates nicely the interplay between pure photoionization dynamics and Rydberg channel couplings, as is often observed... 

The solution to this apparent paradox lies in the photoionization dynamics. Clearly, the form of the parent ion signal depends strongly on the specific photoionization dynamics and, in order to avoid misleading conclusions, must be analyzed for each specific case. The (Koopmans) photoionization correlations of excited-state electronic configurations with those of the cation play a critical role. 

The majority of recent PES studies of the halomethanes has concerned photoionization dynamics, and has employed synchrotron radiation sources. Halomethanes are aptly suited for such studies because they exhibit a relatively small number of well-resolved PES bands and contain atoms of very different atomic number, Z. This variation of Z permits fine tuning of the molecular ion potential and opens a window for the study of photoelectron-ion interactions. In addition, the Br3d and I4d shells have large photoionization cross-sections in the SXR region, thus extending the scope of PES studies from the valence to the outer-core electrons. 

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