Interaction of the low-pressure mercury discharge with soda-lime glass

Abstract

The interaction of the low-pressure mercury discharge with soda-lime glass subjected to standard fluorescent lamp processing has been examined. Particular emphasis has been placed on investigating the consequences on optical transmission of the interaction. Two optically distinct effects can be isolated, attributable to bulk ('in-glass') and surface ('on-glass') reactions. The bulk effect appears to be due both to mercury diffusion and to solarisation and approaches completion at 500 h. It is characterised by a strong dependence of absorption on wavelength, this becoming particularly marked only below 400 nm. In contrast the surface effect, due to mercury lay-down, approaches saturation much more slowly and produces a film whose absorption is essentially wavelength independent over the range 300-600 nm.