Unusual two-dimensional angular distribution of photoelectrons of kish graphite and 1T-TaS 2

Abstract

Two-dimensional patterns of angle-resolved photoemission are measured on Kish graphite and 1T-TaS 2 for s-polarized synchrotron radiation. Observed symmetry-broken patterns are theoretically discussed. The effect of the dipole selection rules by the s-polarized light is clarified. It is found for the first time that an interference of photoelectron waves from non-equivalent sites provides uneven intensity distribution in different Brillouin zones. The patterns of 1T-TaS 2 measured at 40 eV are remarkably different from those at 22 eV, which is explained by the resonant photoemission in the Ta 5 p core excitation region breaking the dipole selection rule due to the direct recombination type Auger transition.