Spectra of Hydrogen, Nitrogen and Oxygen in the Extreme Ultraviolet

Abstract

Spectroscopy of Extreme Ultraviolet.—A method which has been developed of coating films with an emulsion suitable for work in this region is described in detail, and also an oil-cooled discharge tube of the internal capillary type which will stand an input of 2.25 KW and thus reduce the time of exposure and consequent fogging of the films from 10 to 100 fold. Transparency of oxygen, nitrogen and air between 500 and 1,800 Å. was investigated. In a vacuum spectrograph with a grating of 50 cm. radius these gases were found to transmit light of from 1100 to 1225 Å. even when at a pressure of 3 cm. At around 1 mm. spectrum lines were photographed from 800 to 1,800 Å. and with oxygen at 0.001 mm., the spectrum was photographed to 430 Å. These gases, then, are not as opaque to light in this region of the spectrum as has been generally supposed.