Using an optically thin single crystal sample, mounted in a cryostat permitting cooling to 6 K, and a synchrotron as a bright light source, exceptionally well defined absorption spectra of well-characterised $\alpha$-glycine have been obtained in the spectral range 2.5–7.5 THz (approximately 80–240 cm⁻¹). Four separate resonances have been observed, respectively at 93, 152, 188, and 223 cm⁻¹ at the lowest temperature. Each reduces in frequency (redshifts) as temperature increases. The origin of this observed behaviour is attributed to a phonon-mediated anharmonicity in the crystal potential.

中文翻译：

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α-甘氨酸的3、5、6和7 THz共振

使用安装在低温恒温器中的光学稀薄单晶样品，可冷却至6 K，并使用同步加速器作为明亮光源，其特征明确的吸收光谱非常清晰 $\alpha$在2.5–7.5 THz（约80–240 cm ^-1）的光谱范围内获得了β-甘氨酸。在最低温度下，分别在93、152、188和223 cm ^-1处观察到四个单独的共振。随着温度的升高，频率降低（红移）。这种观察到的行为的起源归因于晶体电位中的声子介导的非谐性。