Absorption coefficients of oxygen in the vacuum ultraviolet.

Abstract

Absorption coefficients of oxygen were measured between 300A and 1300A using a grazing incidence vacuum spectrograph together with a line emission light source. The coefficients near 1300A were less than k=10 cm−1. The bands in the region between 1300A and 1000A showed strong absorption of the same order of magnitude as in the Worley bands of nitrogen. No strong continuous absorption was found in the region between 1300A and 740A. The continuous absorption of oxygen below 740A was interpreted as composed of the ionization continua of several Rydberg series converging to the excited states of the molecular ion of oxygen. The continuum had a broad maximum with k-values of about 700 cm−1 between 400A and 600A and, in contrast to nitrogen, still showed a large absorption of k=530 cm−1 at 303A. An estimate of the integrated absorption coefficient was made and the corresponding f-value was found to be 6, in agreement with the predictions from classical dispersion theory.