UPGRADE OF VARIABLE FREQUENCY PULSED EPR FACILITY

描述（由申请人提供）： 该提案要求提供资金，通过购置一个高场（1.99特斯拉）磁体系统，包括电源、带附件和温度控制器的液氦低温恒温器以及一个定时/数据采集模块，对亚利桑那大学化学系的变频脉冲EPR设施进行大幅度升级。目前，作为Bruker ESP 300 E X波段CW EPR光谱仪组成部分的单个1.4特斯拉磁体系统还必须满足三种独特的宽带脉冲EPR光谱仪的要求，这些光谱仪的工作频率范围为2-8、8-18和26-40 GHz。这种安排大大限制了EPR设施的研究产出，因为在任何时候只能进行一种EPR实验。此外，单个可用磁体系统的光谱仪之间的频繁更换占用了可用于生产性研究的宝贵仪器时间。此外，现有磁体的1.4特斯拉磁场太低，使得g < 2.0的EPR信号不能通过接近40 GHz的高分辨率脉冲EPR技术来研究。这种高频率范围是必不可少的脉冲EPR研究的几个生物分子的研究人员的这一建议，包括调查的14 N，15 N的相互作用，血红素蛋白和Rieske蛋白和17-O的钼酶，所有这些都有g值低于g=2。所要求的1.99特斯拉磁体系统（带电源）、液氦低温恒温器（带附件和温度控制器）以及定时/数据采集模块，将使用现有的8-18和26-40 GHz脉冲宽带EPR光谱仪处理对金属生物分子实验日益增长的需求，并为用户提供更多的CW X波段和脉冲S/C波段（2-8 GHz）光谱仪

DESCRIPTION (provided by applicant): This proposal requests funding to substantially upgrade the variable frequency pulsed EPR Facility in the Department of Chemistry at the University of Arizona by acquiring a high field (1.99 Tesla) magnet system, including power supply, liquid helium cryostat with accessories and temperature controller, and a timing/ data acquistion module. Presently, a single 1.4 Tesla magnet system that is an integral part of the Bruker ESP300E X-band CW EPR spectrometer must also serve the requirements for the three unique broadband-pulsed EPR spectrometers that operate over the 2-8, 8-18 and 26-40 GHz ranges. This arrangement greatly limits the research output of the EPR Facility because only one type of EPR experiment can be running at any one time. In addition, the frequent changing among the spectrometers for the single available magnet system usurps valuable instrument time that could be used for productive research. Moreover, the 1.4 Tesla field of the existing magnet is too low to enable EPR signals with g < 2.0 to be studied by high resolution pulsed EPR techniques near 40 GHz. This high frequency range is essential for pulsed EPR studies of several of the biomolecules of the investigators of this proposal, including investigation of 14N, 15N interactions in heme proteins and Rieske proteins and 17-O in molybdenum enzymes, all of which have g-values spread below g=2. The requested 1.99 Tesla magnet system with power supply, liquid helium cryostat with accessories and temperature controller, and a timing/data acquisition module, will handle the ever increasing demands for experiments on metallobiomolecules using the existing 8-18 and 26-40 GHz pulsed broadband EPR spectrometers as well as provide increased access of users to the CW X-band and pulsed S/C band (2-8 GHz) spectrometers.