Sharp Line Absorption in Silica near 3400 cm^−1*

Sharp absorption lines have been observed at temperatures near 4°K in samples of fused silica and crystal quartz. The strongest lines are near 3365 cm−1 and 3472 cm−1 and have widths at half height of less than 2.5 cm−1. With increasing temperature the absorption lines are shifted to higher frequencies; in addition, the lines are broadened and the peak absorption is decreased.