Departamento de Física, Universidade Federal do Ceará, C.P. 6030 60455-760 Fortaleza CE, Brazil.
Chemphyschem. 2009 Dec 21;10(18):3337-43. doi: 10.1002/cphc.200900482.
Raman and neutron experiments using specific isotope labeling were combined in order to study the dynamics and structure of L-alanine. Inelastic neutron and Raman scattering data of C(2)H(4)(ND(2))CO(2)D are discussed in relation to the doubling of the lattice parameter a observed by means of neutron powder diffraction in C(2)D(4) (NH(2))CO(2)H. The major changes accompanying the phase transition are found in the vibrational frequencies involving the torsional vibration tau(CO(2)(-)), which is clearly affected by the hydrogen bonds between the protons of the ammonium group and the oxygen atoms of the carboxylate group. At lower temperatures the rearrangement of identifiable hydrogen bonds induces changes in the bending vibration delta(ND(3)), confirming some orientational disorder.
拉曼和中子实验采用特定的同位素标记相结合，以便研究 L-丙氨酸的动力学和结构。C(2)H(4)(ND(2))CO(2)D 的非弹性中子和拉曼散射数据与通过中子粉末衍射在 C(2)D(4)(NH(2))CO(2)H 中观察到的晶格参数 a 的加倍有关。在相变过程中，伴随着振动频率的主要变化涉及扭转振动 tau(CO(2)(-))，这显然受到铵基团的质子与羧酸盐基团的氧原子之间氢键的影响。在较低的温度下，可识别氢键的重排引起弯曲振动 delta(ND(3))的变化，证实了一定的取向无序。
