The self-trapped exciton luminescence in the glass is not as effective as in α-
quartz crystal. The UV band in studied glass under x-ray excitation
contains two subbands in UV one at 3.9 eV and one at 4.9 eV both
strongly increasing in intensity with cooling to 80 K (figures for
glasses are omitted for shortening the paper). It is assumed that
both bands at 3.9 eV and at 4.9 eV belong to presence of
phosphorus in phosophosilicate glass as well.