Department of Chemistry, 1-014 Center for Science and Technology, Syracuse University, Syracuse, NY 13244-4100, USA.
Phys Chem Chem Phys. 2009 Nov 7;11(41):9474-83. doi: 10.1039/b905070a. Epub 2009 Aug 21.
The 2 : 1 amino acid salt of L-alanine with nitric acid was crystallized and the vibrational spectrum measured at 25 K by incoherent inelastic neutron scattering (INS) spectroscopy. The spectrum was simulated using solid-state density functional theory based on a new 90 K structure determination. A feature observed at approximately 450 cm(-1) in the INS spectrum of L-alanine alaninium nitrate is noticeably absent in the calculation. Raman spectroscopy reveals spectral differences between the spectra at 77 and 293 K with a 450 cm(-1) feature appearing at low temperature. The nature of these spectral changes and the disagreement between the INS spectrum and its simulation are discussed in relation to an apparent structural change involving motion of a proton at low (<90 K) temperature.
L-丙氨酸与硝酸以 2:1 的比例形成的氨基酸盐被结晶，并在 25 K 下通过非相干非弹性中子散射（INS）光谱法测量其振动光谱。该光谱使用基于新的 90 K 结构确定的基于固态密度泛函理论进行了模拟。在 INS 光谱中，大约在 450 cm(-1)处观察到的 L-丙氨酸硝酸丙氨酸的特征在计算中明显不存在。拉曼光谱揭示了 77 和 293 K 之间的光谱差异，低温下出现 450 cm(-1)特征。这些光谱变化的性质以及 INS 光谱与其模拟之间的差异与涉及质子在低温（<90 K）下运动的明显结构变化有关。
