沸石咪唑盐骨架
甲基
中子衍射
化学
咪唑酯
激发态
中子散射
氘
非弹性中子散射
散射
基态
结晶学
转动能
衍射
原子物理学
分子物理学
物理化学
无机化学
晶体结构
物理
有机化学
吸附
金属有机骨架
光学
群(周期表)
作者
Wei Zhou,Hui Wu,Terrence J. Udovic,J. J. Rush,Taner Yildirim
摘要
Using neutron inelastic scattering and diffraction, we have studied the quantum methyl rotation in zeolitic imidazolate framework-8 (ZIF-8: Zn(MeIM)(2), MeIM = 2-methylimidazolate). The rotational potential for the CH(3) groups in ZIF-8 is shown to be primarily 3-fold in character. The ground-state tunneling transitions at 1.4 K of 334 +/- 1 mueV for CH(3) groups in hydrogenated ZIF-8 (H-ZIF-8) and 33 +/- 1 mueV for CD(3) groups in deuterated ZIF-8 (D-ZIF-8) indicate that the barrier to internal rotation is small compared to almost all methylated compounds in the solid state and that methyl-methyl coupling is negligible. A 2.7 +/- 0.1 meV scattering peak assigned to the ground-state to first-excited-state, hindered rotational transition for H-ZIF-8, combined with a approximately 3 meV activation energy for methyl-group 3-fold jump reorientation estimated by quasi-elastic neutron scattering, suggests a very low methyl rotational barrier of approximately 7 meV. Results are compared to the CH(3) rotational amplitude at 3.5 K derived from neutron diffraction data, which are also consistent with a small 3-fold barrier and a very low energy rotational oscillation.
科研通智能强力驱动
Strongly Powered by AbleSci AI