Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne, EPFL, Batochime, 1015 Lausanne, Switzerland.
J Magn Reson. 2010 Jul;205(1):177-9. doi: 10.1016/j.jmr.2010.04.014. Epub 2010 Apr 27.
By combining indirect detection of 14N with dynamic nuclear polarization (DNP) using a gyrotron, the signal-to-noise ratio can be dramatically improved and the recovery delay between subsequent experiments can be shortened. Spectra of glassy samples of the amino acid proline doped with the stable bi-radical TOTAPOL rotating at 15.625 kHz at 110K were obtained in a 400 MHz solid-state NMR spectrometer equipped with a gyrotron for microwave irradiation at 263 GHz. DNP enhancement factors on the order of epsilon approximately 40 were achieved. The recovery delays can be reduced from 60 s without radicals at 300 K to 6 s with radicals at 110 K. In the absence of radicals at room temperature, the proton relaxation in proline is inefficient due to the absence of rotating methyl groups and other heat sinks, thus making long recovery delays mandatory. DNP allows one to reduce the acquisition times of 13C-detected 14N spectra from several days to a few hours.
通过将 14N 的间接检测与使用回旋管的动态核极化 (DNP) 相结合，可以显著提高信噪比，并缩短后续实验之间的恢复延迟。在配备回旋管的 400 MHz 固态 NMR 光谱仪中，以 15.625 kHz 的速度旋转的稳定双自由基 TOTAPOL 掺杂的脯氨酸玻璃状样品在 110K 下获得了光谱，回旋管用于在 263GHz 处进行微波辐照。DNP 增强因子约为 epsilon 约为 40。在没有自由基的情况下，恢复延迟可以从 300 K 时的 60 秒减少到 110 K 时的 6 秒。在室温下没有自由基时，由于没有旋转的甲基和其他散热源，脯氨酸中的质子弛豫效率不高，因此必须延长恢复延迟。DNP 可以将 13C 检测到的 14N 谱的采集时间从数天缩短到数小时。
