Determination of phase differences of transition matrix elements from Pt(110) by means of spin-resolved photoemission with circularly and linearly polarized radiation

Abstract

For Pt(110)-(1×2), the phase difference between the complex transition dipole matrix elements M (3) ‖ and M (4) ‖, i.e. the dipole matrix elements for transitions from initial states of double-group symmetry Σ 5 with spatial parts Σ 3 5 and Σ 4 5 of single-group symmetry Σ 3 and Σ 4, respectively, to final states of double-group symmetry Σ 5 with the spatial part Σ 1 5 of single-group symmetry Σ 1, has been determined quantitatively by means of spin-resolved photoemission spectroscopy. The measurements were performed at the BESSY 6.5 m NIM with circularly and linearly polarized synchrotron radiation using a photon energy of 11.8 eV in the highly symmetrical set-up of normal incidence and normal emission. The experimental results obtained with the linearly polarized radiation show very good agreement with a recent theoretical prediction of Henk and Feder [Europhys. Lett. 28 (1994) 609]. The phase difference determined is interpreted to be the physical origin of the non-vanishing electron spin polarization in the experiments with linearly polarized radiation. Within an atomic model, the alignment of the atoms on the surface is shown to be the physical origin of the effect.