Eur. Phys. J. B 23, 69-77 (2001)
https://doi.org/10.1007/s100510170083

Strong impact of the electron-photon matrix element on angle-resolved photoelectron spectra of Sr₂CuO₂Cl₂

Department of Physics and Astronomy and Ames Laboratory, US Department of Energy, Iowa State University, Ames, Iowa 50011, USA

Received: 10 January 2000
Revised: 15 January 2001
Published online: 15 September 2001

Abstract

In recent years insight has been gained into the electronic structure of layered cuprates using angle-resolved photoelectron spectroscopy. In many of these studies it is assumed that the electron-photon matrix element follows the trends set by the atomic photoionization cross sections and does not influence lineshape, dispersion and the k-dependence of the spectral intensity. In this study using Sr₂CuO₂Cl₂ as an example it will be shown that the electron-photon matrix element can have a strong impact on both strength and shape of a feature in an angle-resolved photoelectron spectrum of a layered cuprate which can strongly affect information on character and the momentum-dependence of the energy and spectral weight of a state deduced from the spectra. The results of this study put an emphasis on the need to employ the whole parameter range of the ARPES method to get reliable information on the spectral function of cuprates for which purpose synchrotron radiation is an uniquely suited tool.