Cryogenic NMR spectroscopy of endohedral hydrogen-fullerene complexes
Cryogenic NMR spectroscopy of endohedral hydrogen-fullerene complexes
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DOI：
10.1063/1.2174012
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发表时间：
2006-03-14
影响因子：
4.4
通讯作者：
Komatsu, K
中科院分区：
文献类型：
--
作者：
Carravetta, M;Johannessen, OG;Komatsu, K
在低温条件下，我们观察到了被困在改性富勒烯笼中的氢分子的H-1 NMR谱。静态样品上的实验在样品温度下进行到4.3 K，而魔角旋转（MAS）实验在温度下进行到20 K，旋转频率为15 kHz。这两种类型的NMR谱显示在低于50 K的温度下，分子内H-1-H-1偶极耦合的大幅增加，揭示了少量的空间旋转状态的热选择。静态和MAS光谱进行了比较，以估计在高速低温MAS-NMR实验样品加热的程度。低温MAS-NMR数据表明，魔角旋转NMR的位置分辨能力可以与低温操作的高信号强度相结合，低温现象可以用化学位置选择性来研究。
We have observed H-1 NMR spectra of hydrogen molecules trapped inside modified fullerene cages under cryogenic conditions. Experiments on static samples were performed at sample temperatures down to 4.3 K, while magic-angle-spinning (MAS) experiments were performed at temperatures down to 20 K at spinning frequencies of 15 kHz. Both types of NMR spectra show a large increase in the intramolecular H-1-H-1 dipolar coupling at temperatures below 50 K, revealing thermal selection of a small number of spatial rotational states. The static and MAS spectra were compared to estimate the degree of sample heating in high-speed cryogenic MAS-NMR experiments. The cryogenic MAS-NMR data show that the site resolution of magic-angle-spinning NMR may be combined with the high signal strength of cryogenic operation and that cryogenic phenomena may be studied with chemical site selectivity.