Analytical Sciences

24 T High-Resolution and -Sensitivity Solid-State NMR Measurements of Low-Gamma Half-Integer Quadrupolar Nuclei ³⁵Cl and ³⁷Cl

Manoj Kumar PANDEY,*1,*2 Kenjiro HASHI,*3 Shinobu OHKI,*3 Gen NISHIJIMA,*3 Shinji MATSUMOTO,*3 Takashi NOGUCHI,*3 Kenzo DEGUCHI,*3 Atsushi GOTO,*3 Tadashi SHIMIZU,*3 Hideaki MAEDA,*1,*4 Masato TAKAHASHI,*1,*4 Yoshinori YANAGISAWA,*1,*4 Toshio YAMAZAKI,*1,*4 Seiya IGUCHI,*4 Ryoji TANAKA,*2 Takahiro NEMOTO,*2 Tetsuo MIYAMOTO,*2 Hiroto SUEMATSU,*2 Kazuyoshi SAITO,*5 Takashi MIKI,*5 and Yusuke NISHIYAMA*1,*2

*1 RIKEN CLST-JEOL Collaboration Center, RIKEN, Yokohama, Kanagawa 230-0045, Japan
*2 JEOL RESONANCE Inc., Musashino, Akishima, Tokyo196-8558, Japan
*3 National Institute for Materials Science, Sakura, Tsukuba, Ibaraki 305-0003, Japan
*4 Center for Life Science Technologies, RIKEN, Yokohama, Kanagawa 230-0045, Japan
*5 Kobe Steel Ltd., Kobe, Hyogo 651-2271, Japan

Solid-state NMR observations of low-gamma half-integer quadrupolar nuclei, ³⁵Cl and ³⁷Cl, were demonstrated using a 24 T hybrid magnet (¹H resonance frequency of 1.02 GHz) comprised of the high-temperature (HTS) and low-temperature (LTS) superconductors, and compared with results using a 14.1 T standard NMR magnet. While at 24 T the linewidth is 1.7 times narrower than that at 14.1 T, the gain in the sensitivity is 7.0 times because of enhanced polarization, reduced linewidth, and the use of larger rotor. A simple theoretical model was used to rationalize the sensitivity enhancements. The ratio of ³⁵Cl and ³⁷Cl quadrupolar couplings agrees well with the ratio of quadrupolar moments, and no isotope-dependent chemical shift has been observed. In addition, the 3QMAS spectrum of ³⁵Cl is shown to demonstrate the high sensitivity rendered by the 24 T spectrometer.

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