Optically Polarized Conduction-Band Electrons in Tungsten Observed by Spin-Polarized Photoemission

Along the (100) direction of tungsten, interband transitions induced by circularly polarized light of energy $1.5 \mathrm{eV}<~h\nu <~4.1 \mathrm{eV}$ lead to spin polarization of the excited conduction electrons. This is observed by measuring the spin polarization of the photoelectrons emitted from a cesiated crystal surface. The measured polarization values depend sensitively on the $s$-, $p$-, and $d$-hybridization properties of the conduction bands. Excited-state lifetimes are obtained from the widths of the polarization structures.