摘要

We describe the design and operation of a time-of-flight electron spectrometer which is capable of simultaneously acquiring the energy and momentum distribution of low-energy photoelectrons in two dimensions parallel to the surface. We discuss its capabilities and limitations in particular for time- and angle-resolved two-photon photoemission (2PPE) with pulsed lasers. The performance of the spectrometer is demonstrated by presenting 2PPE data on the momentum-dependent electron dynamics of the first (n=1) image-potential state on Cu(001). The data reveal a weak but systematic dependence of the decay dynamics on sample azimuth with one-fold symmetry which we attribute to a small residual step density on the nominal flat surface.

  • 出版日期2015-7