کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5406042 | 1506047 | 2012 | 9 صفحه PDF | دانلود رایگان |
We describe the design and initial performance results of a multi-sample dissolution dynamic-nuclear-polarization (DNP) polarizer based on a Helium-temperature NMR cryostat for use in a wide-bore NMR magnet with a room-temperature bore. The system is designed to accommodate up to six samples in a revolver-style sample changer that allows changing samples at liquid-Helium temperature and at pressures ranging from ambient pressure down to 1Â mbar. The multi-sample setup is motivated by the desire to do repetitive in vivo measurements and to characterize the DNP process by investigating samples of different chemical composition. The system can be loaded with up to six samples simultaneously to reduce sample loading and unloading. Therefore, series of experiments can be carried out faster and more reliably. The DNP probe contains an oversized microwave cavity and includes EPR and NMR capabilities for monitoring the DNP process. In the solid state, DNP enhancements corresponding to â¼45% polarization for [1-13C]pyruvic acid with a trityl radical have been measured. In the initial liquid-state acquisition experiments described here, the polarization was found to be â¼13%, corresponding to an enhancement factor exceeding 16,000 relative to thermal polarization at 9.4Â T and ambient temperature.
60Highlights⺠A multi-sample dissolution DNP polarizer accommodating up to six samples. ⺠Revolver-style sample changer operating at cryo temperature and pressures down to 1 mbar. ⺠Oversized microwave cavity allows DNP-saturation with power levels of less than 20 mW. ⺠13C-polarization levels of up to 25% in the liquid state and 45% in the solid state.
Journal: Journal of Magnetic Resonance - Volume 214, January 2012, Pages 166-174