The IR absorption spectrum of high purity photo-thermo-refractive (PTR) glasses melted under atmosphere containing different concentrations of water is studied. The absorption spectra of the water and glass matrix are separated and deconvoluted to elementary Gaussian bands. The water absorption spectrum includes 11 bands with a maxima at 4320, 3560, 3053, 2897, 2815, 2765, 2525, 2315, 2219, 2150, and 1908 nm. The current technology provides a decrease of the decimal absorption coefficient at 2800 nm from 0.4 to 0.04 cm^-1. The PTR glass matrix absorption spectrum includes three bands at 4855, 3950, and 3250 nm (2060, 2532, and 3077 cm^-1). The long wavelength absorption edge for the PTR glass matrix is 2900 nm for the decimal absorption coefficient 0.01 cm^-1, 3600 nm for 0.1 cm^-1, and 4200 nm for 1 cm^-1.

中文翻译：

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光热折射玻璃的长波长光吸收边

研究了在含有不同浓度水的气氛下熔化的高纯光热折射（PTR）玻璃的红外吸收光谱。水和玻璃基质的吸收光谱被分离并解卷积到基本高斯带。吸水光谱包括 11 个波段，最大值分别为 4320、3560、3053、2897、2815、2765、2525、2315、2219、2150 和 1908 nm。目前的技术提供了在 2800 nm 处的十进制吸收系数从 0.4 到 0.04 cm ^{-1 的降低}。PTR 玻璃基体吸收光谱包括 4855、3950 和 3250 nm（2060、2532 和 3077 cm ^-1）的三个波段。PTR 玻璃基体的长波长吸收边为 2900 nm，十进制吸收系数为 0.01 cm ^-1，0.1 cm ^-1为 3600 nm，1 cm ^-1为 4200 nm 。