Increased 1H combined rotation and multiple pulse spectroscopy (CRAMPS) linewidths for protons within NH3+ groups in the solid state have been investigated by variable-temperature experiments. Linewidth variation with temperature can be correlated with specific molecular dynamic processes. With L-[15N]-alanine, both the NH3+ and CH3 group reorientations give rise to specific broadening of the respective CRAMPS signals as the temperature is lowered. Such dynamic processes may be more important than 14N-1H quadrupolar-modified dipolar broadening in determining NH3+ proton lineshapes.
通过变温实验研究了固态 NH3+ 基团内质子的 1H 组合旋转和多脉冲光谱 (C
RAMPS) 线宽的增加。线宽随温度的变化可以与特定的分子动力学过程相关。对于 L-[15N]-丙
氨酸,随着温度降低,NH3+ 和
CH3 基团重新定向都会导致相应 C
RAMPS 信号的特定加宽。在确定 NH3+ 质子线形时,这种动态过程可能比 14N-1H 四极修改偶极展宽更重要。