Spectroscopic investigation of the electronic structure of the hole-doped one-dimensional cuprates Ca<SUB>2</SUB>CuO<SUB>3</SUB> and Sr<SUB>2</SUB>CuO<SUB>3</SUB>

We investigate the effect of hole doping in the electronic structure of covalent insulators, Ca2CuO3 and Sr2CuO3 by means of photoelectron spectroscopy. The changes in the core level, valence-band and conduction-band spectra indicate a doping-induced small modification in the interaction parameters. The doped holes are found to be localized primarily at the apical oxygen sites