Location of Optical Transitions ink→space from Angular Photoemission Measurements on W

Abstract
The energy and emission angle of electrons photoemitted from the (110) and (111) surfaces of W have been measured for photon energies between 7.7 and 10.7 eV. For prominent transitions, the component of internal k vector tangential to the surface was obtained from angular measurements on each of the two surfaces. The two components of k were used to determine the internal k vector of prominent transitions occurring in the plane defined by the 110 and 111 axes.