Abstract

Raman scattering (RS) spectra in lithium tantalate single crystals are studied at 180-degree scattering geometry in a wide frequency spectral range (50–2500 cm^–1). RS intensity peaks corresponding to fundamental transverse (TO) and longitudinal (LO) polar optical modes of this crystal are recorded. It is found that the high-frequency spectral range (1300–2000 cm^–1) contains RS intensity peaks whose frequencies exceed doubled frequencies of A₁- and E-type fundamental vibrations of the LiTaO₃ lattice. The intensity of these peaks appeared comparable to the intensity of lines corresponding to A₁- and E-type fundamental transverse and longitudinal polar optical modes. The conditions of the appearance of bound states of polar phonons in the RS spectra of lithium tantalate crystal are analyzed.

中文翻译：

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钽酸锂单晶中极性基模的泛音态对拉曼光的散射

摘要

钽酸锂单晶体的拉曼散射（RS）光谱是在宽光谱范围（50–2500 cm ^–1）内以180度散射几何形状进行研究的。记录与该晶体的基本横向（TO）和纵向（LO）极性光学模式相对应的RS强度峰。发现高频频谱范围（1300–2000 cm ^–1）包含RS强度峰值，其频率超过LiTaO ₃晶格的A ₁和E型基本振动频率的两倍。这些峰的强度看起来可与对应于A _1-和E的谱线的强度相媲美型基本的横向和纵向极光学模式。分析了钽酸锂晶体RS光谱中极性声子的束缚态出现条件。