On the use of x-ray reflectivity and fluorescence as probes of the longitudinal structure of the liquid–vapor interface.

The x-ray reflectivity and fluorescence, as functions of angle of incidence and angle of detection, are calculated for several models of the longitudinal density distribution in the liquid–vapor interface. The models studied range from one descriptive of the monotone density distribution in a dielectric liquid–vapor interface to one descriptive of the stratified density distribution predicted for the metal liquid–vapor interface. In addition, we report calculations for the liquid–vapor interfaces of several simple binary alloys, each characterized by varying degrees of surface segregation of the components. Our results suggest that x-ray reflectivity and fluorescence intensity variations with angle of incidence and angle of detection can be sensitive probes of density and composition variations along the normal to the interface for pure metals and alloys. [ABSTRACT FROM AUTHOR]