Photoelectron escape depth and inelastic secondaries in high-temperature superconductors

We calculate the photoelectron escape depth in the high-temperature superco nductor Bi2212 by use of electron energy-loss spectroscopy data. We find th at the escape depth is only 3 Angstrom for photon energies typically used i n angle-resolved photoemission measurements. We then use this to estimate t he number of inelastic secondaries, and find this to be quite small near th e Fermi energy. This implies that the large background seen near the Fermi energy in photoemission measurements is of some other origin. [S0163-1829(9 9)08017-0].