Raman spectra of (As_1–xBi_x)₂S₃ glass samples with x ≤ 0.2 measured at the excitation with above-bandgap (532 nm) laser light at a relatively low power density (P_exc = 4 kW/cm²) clearly confirm the amorphous character, thereby markedly extending the known compositional interval of existence of the (As_1–xBi_x)₂S₃ glass previously known (x ≤ 0.06). Spectra measured at an increased P_exc (40 kW/cm²) reveal a photostructural transformation in the illuminated area of the glass leading to an additional contribution of Bi–S bonds as well as to an increasing number of cage-type As₄S₄ units with homopolar As–As bonds. A number of new features in a broad range up to about 1,000 cm⁻¹, which emerge in the Raman spectra of the (As_1–xBi_x)₂S₃ glasses with high (x ≥ 0.14) Bi content and increase in intensity with the exposure time, are related to a photochemical transformation, namely, oxidation of arsenic and sulphur on the (As_1–xBi_x)₂S₃ glass surface with formation of units containing arsenate AsO₄³⁻ and sulphate SO₄²⁻ ions. These processes are irreversible and occur only in the presence of a sufficient amount of bismuth.

中文翻译：

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拉曼光谱观察 (As1–xBix)2S3 玻璃中的光致转变

x ≤ 0.2 的 (As _{1– x} Bi _x ) ₂ S ₃玻璃样品的拉曼光谱是在相对较低的功率密度 ( P _exc  = 4 kW/cm ² ) 的高于带隙 (532 nm) 激光的激发下测量的清楚地证实了非晶态特征，从而显着扩展了先前已知的(As _{1– x} Bi _x ) ₂ S _3玻璃( x  ≤ 0.06)存在的已知成分区间。在增加的P _exc (40 kW/cm ² ) 下测量的光谱揭示了玻璃照明区域的光结构转变，导致 Bi-S 键的额外贡献以及笼型 As ₄ S ₄数量的增加具有单极 As-As 键的单元。在高达约 1,000 cm ^{-1 的}广泛范围内出现了许多新特征，这些特征出现在具有高 ( x  ≥ 0.14) Bi 含量且强度增加的 (As _{1– x} Bi _x ) ₂ S ₃玻璃的拉曼光谱中随曝光时间的变化与光化学转化有关，即砷和硫在 (As _{1– x} Bi _x ) ₂ S ₃玻璃表面氧化，形成含有砷酸盐 AsO ₄ ³⁻和硫酸盐 SO ₄ ²⁻的单元。离子。这些过程是不可逆的，并且只有在足够量的铋存在的情况下才会发生。