Photoelectron spectroscopy is well suited for the determination of solute density profiles across the aqueous interface. Here one exploits the element specificity of the technique and the electron probing depth. However, the potential correlation between measured (core-level) electron signal and solute abundance is complicated by hitherto poorly characterized photoionization parameters. Of particular concern is the photoemission angular distribution (PAD) which is studied here using the O1s ionization of liquid water over a wide range of energies and compared to water vapor.  The PAD measured from the liquid is anisotropic, suggesting elastic scattering does not completely mask useful information on the electronic structure and molecular orientation of the ionized molecule. However the PAD is more isotropic than for water vapor and from our data we can assess the relative importance of elastic and inelastic scattering of the departing electron as a function of outgoing kinetic energy.  The first PADs for molecular solutes at the aqueous interface are also presented.

Photoelectron angular distribution from liquid water surface: Implications for structure and probing depth

244th National Meeting (2012)

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