A new spin effect in photoemission with unpolarized light: Experimental evidence of spin polarized electrons in normal emission from Pt(111) and Au(111)

Unpolarized light ejects spin polarized electrons from Pt(111) and Au(111) even if the electron emission occurs normal to the surface. For off normal incidence of 11.8 eV, 16.9 eV, and 21.2 eV radiation, and for the main peaks in the photoemission spectra, a degree of spin polarization of up to 30% or more is found for the spin polarization component P_yperpendicular to the reaction plane. A crystal rotation about its surface normal does not change P_y. P_yis largest for transitions from bands with symmetry ₆³. All these experimental findings agree with a recent theoretical prediction [1] of a new spin effect by Tamura and Feder.