Andrew E R, Peplinska B, Kempka M
Department of Physics, University of Florida, Gainesville 32611, USA.
Solid State Nucl Magn Reson. 1998 Jan;10(3):117-21. doi: 10.1016/s0926-2040(97)00077-5.
Proton NMR measurements of the spectrum, second moment, spin-lattice relaxation time T1 and dipolar relaxation time T1D were carried out on polycrystalline L-adrenaline at 14 and 25 MHz between 55 and 400 K. Between 70 K and 250 K relaxation is dominated by C3 reorientation of the single methyl group in each molecule, characterized by an activation energy 8.3+/-0.3 kJ/mole. Below 70 K tunnelling assisted relaxation is significant, characterized by an excitation energy of 1.9+/-0.2 kJ/mole. Above 250 K an additional molecular motion becomes significant, with activation energy above 28 kJ/mole, attributed to conformational motion of the methylene group in the ethylamine side chain.
在55至400K的温度范围内，于14和25MHz频率下对多晶型L-肾上腺素进行了质子核磁共振谱、二阶矩、自旋晶格弛豫时间T1和偶极弛豫时间T1D的测量。在70K至250K之间，弛豫主要由每个分子中单个甲基的C3重取向主导，其特征在于活化能为8.3±0.3kJ/mol。在70K以下，隧道辅助弛豫显著，其特征在于激发能为1.9±0.2kJ/mol。在250K以上，另一种分子运动变得显著，活化能高于28kJ/mol，这归因于乙胺侧链中亚甲基的构象运动。
