PROJECT SUMMARY/ABSTRACT
This application is for a Bruker ELEXSYS-II E500 X-band continuous wave (CW) electron paramagnetic
resonance (EPR) spectrometer system with temperature control to replace our failing 22-year-old Bruker
ELEXSYS E500 instrument. The new Bruker ELEXSYS-II E500 boasts 10-fold greater sensitivity, runs on a
solid-state power source, has a digital signal processing unit (SPU), and contains an ultra-low-noise microwave
source and a digital rapid field scan module. In all ways, this is a completely advanced version of our obsolete
and unreliable system. The importance of this instrument to the success of the multiple NIH-funded and future
projects is paramount, and, thus, it is imperative that we have a reliable CW EPR spectrometer. A brand-new
Bruker X-band ELEXSYS-II E500 CW EPR spectrometer will replace, and even extend, the capabilities of our
current workhorse CW spectrometer in the National Biomedical EPR Center at the Medical College of Wisconsin.
Along with increased reliability and stability, the new instrument has significantly improved sensitivity due to
modern and improved digital and solid-state parts. In addition, the requested temperature control accessory will
extend our capability to maintain accurate sample temperature in the range of 3.8–350 K. This modern
technology, which is designed primarily as a research platform for a wide variety of applications such as structural
biology, enzyme reactions, redox biology, membrane studies, drug discovery, and technology development, is
ideally suited to the specific types of NIH-funded biomedical projects outlined here for a group of 7 Major Users
and 7 Minor Users. The Bruker ELEXSYS-II E500 spectrometer is an invaluable asset that will allow us to fulfill
our NIH grant obligations and extend our collaborative scientific investigations at MCW and in the surrounding
community; it is essential to the continued excellence of our research programs.