Absorption coefficients of O₂at the Lyman-alpha line and its vicinity

By means of a 3-m vacuum spectrometer, absorption coefficients of O2 at the Lyman-alpha line and its vicinity have been remeasured between 1214.8 and 1217.8 A. Coefficients at the wavelengths of the apparent doublet peaks of the Lyman-alpha line, caused by self-absorption and separated by 0.09 A, are pressure independent at relatively low pressure (p ≤ 6.3 torr). The absorption coefficient at the shorter wavelength peak is 0.304 ± 0.002 cm−1, and that at the longer wavelength peak is 0.278 ± 0.002 cm−1. The minimum of the transmission window is located at about 1216.0 A, and its value is 0.254 cm−1.