  We calculate the photoelectron escape depth in the high temperature
superconductor Bi2212 by use of electron energy-loss spectroscopy data. We find
that the escape depth is only 3 Ang. for photon energies typically used in
angle resolved photoemission measurements. We then use this to estimate the
number of inelastic secondaries, and find this to be quite small near the Fermi
energy. This implies that the large background seen near the Fermi energy in
photoemission measurements is of some other origin.
