This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. ACERT, as a national center for research and development in ESR spectroscopy, is committed to a comprehensive program of advanced instrumentation specification, design and construction. We are presently in the construction phase on several major spectrometer projects, such as multiband heterodyne and 35GHz pulsed instruments, spectrometers for c.w. and pulse microimaging and control electronics for our improved 170 and 240GHz c.w. sources. In addition, we are continuing our upgrade and repair of the existing ACERT spectrometers, which requires construction of new electronic modules and repair of old ones. Upgrade projects include construction of a new timing system for the 95GHz pulsed spectrometer, field-stepping drivers for HF DEER experiments and fast r.f. switches for microwave receiver protection. Until this past year, we have been able to successfully construct instrumentation in shared laboratory space, but the commissioning of new spectrometers and related experiments in that space has mandated the creation of a new assembly facility elsewhere. To address this requirement, we have renovated a previously unoccupied storage room in order to bring it up to the level of a convenient, comfortable and comprehensive working area. In order to do this, we removed all our cached items to an off-campus long-term storage facility. The University was then persuaded to rehabilitate the room, which was in need of cleaning, repairs, and paint, along with requisite utilities upgrades for the assembly facility. Finally, we installed 18 linear feet of semi-permanent workbenches and approximately 300 sq. ft. of shelving for storage of mechanical and electronic components, and instrument modules in production. The facility is fully equipped with tools for precision mounting and reworking of surface-mount and other sub-miniature components, and a suitable binocular microscope has also been acquired for this work. Use of this facility commenced on a regular basis in mid-1st quarter of 2004.