Ultraviolet transmission changes in glass as a function of the wave length of the radiation stimulus

Abstract

Continuing the research previously reported in Research Paper 113 further consideration is given to methods of testing the photochemical stability of window glass made for transmitting short wave length ultraviolet solar radiation. It is shown that accelerating the stabilization of the transmission of window glass (equivalent to the stabilization produced by sunlight) by means of filtered ultraviolet radiation from the quartz mercury arc is impracticable principally because of the antagonistic action of radiation of wave lengths in the region of about 365 inn which reverses, in varying degrees, the photochemical reaction produced by the shorter wave lengths. A new phenomenon in the ultraviolet transmission behavior of certain glass is reported. The phenomenon may be briefly described as follows: When irradiated with light of a given wave length (in the region 250 to 365 mn) the sample of glass reaches an equilibrium state in which the transmission (at 302 m/x, for example,) attains a certain value, which is a constant for the given wave length stimulus.

An Alkaline Solution of Potassium Chromate as a Transmittancy Standard in the Ultraviolet*

“…Not only do all but a few special glasses absorb completely below 290 m/x, but, in addition, the ultraviolet spectral transmittances of many glasses change on exposure to strong ultraviolet radiant flux [2, 3,4]. In these respects solutions in cells with quartz end plates are found to be superior to glasses for use in the ultraviolet.…”

“…3 Photoelectric Spectrophotometry Group of England has recently conducted a collaborative test on the use of K2Cr207 [6]. 4 Solutions can, of course, also be used in the visible region. In fact, the aqueous solutions of copper sulfate and cobalt ammonium sulfate used in the Davis-Gibson filters [7,8,9,10] have been recommended for that purpose.…”

Ultraviolet radiation physics and the skin

“…The earlier form of the curve had a major peak of activity at 297 nm, a minimum at 280 nm, and a second but lesser peak at 250 nm (Hausser and Vahle 1922,1927, Luckiesh et a1 1930, Coblentz et a1 1931. These different curves showed close agreement from approximately 270 nm to 310 nm and so from these reports a 'standard erythemal curve' was proposed by Coblentz and Stair (1934) and adopted by the International Commission on Illumination (1935). This double peaked curve was accepted as standard for many years but more recent work suggests that the peak at 250 nm is in fact higher than that at 297 nm (Rottier 1954, Magnus 1964, Everett etal 1965, Freeman etal 1966, Berger et a1 1968, Cripps and Ramsay 1970, MacKenzie and Frain-Bell 1973.…”

Permanence of glass standards of spectral transmittance

“…It is possible, of course, that the cobalt blue glas might solarize at shorter wavelength. Those interested in this effect hould r ead the papers by Coblentz and tair, who m ade an exten ive study of the ultraviolet solarization of window glasse and other materials (10,11] .…”