  We have studied the line shapes of ultraviolet photoemission spectra of
La$_{0.7}$Sr$_{0.3}$Mn$_{1-\delta}$Al$_\delta$O$_3$ ($\delta$ = 0, 0.03, 0.06)
systems to test the extrinsic image charge screening effect on photoemission
spectra recently suggested by R. Joynt (Science {\bf 284}, 777 (1999)), who
argued that the photoemission spectrum near the Fermi energy, specially for
poorly conducting system, can be very different from the intrinsic density of
states because the outgoing electron has probability of losing its kinetic
energy due to the image force. We tested this argument in real materials
experimentally by measuring the photoemission line shapes of
La$_{0.7}$Sr$_{0.3}$Mn$_{1-\delta}$Al$_\delta$O$_3$ systems, for which all the
requirements of this theory are satisfied and sample resistivities change
systematically. We found that experimental photoemission spectra do not show
the change of line shapes expected from the extrinsic image force effect and we
conclude that the influence of this long range interaction is not so large as
suggested in that paper.
