Powerful Solid-State Sources to Enable Advanced EPR and DNP-NMR Measurements NIH SBIR Phase II Proposal VDI Project Summary/Abstract: DNP-NMR and EPR are important scientific tools that are of interest to the NIGMS Division of Cell Biology and Biophysics. They both rely on a high frequency microwave source to increase the polarization of electrons in the samples under test. In the past, progress in DNP-NMR and EPR has been hindered by the difficulty of generating sufficient power levels at the desired frequencies, which now extend well above 100 GHz. Typical systems rely on a Gyrotron oscillator that generates tens of watts of power. However, these systems are expensive to purchase and install, and even the operating and maintenance costs can be prohibitive. The key focus of this project is to advance solid-state (SS) source technology to the point where it can begin to replace the Gyrotrons for a significant proportion of DNP-NMR and pulsed-EPR measurements, thereby lowering the barriers to entry into this field and accelerating the pace of scientific discovery. The solid-state sources will also enable advanced modulation schemes that greatly improve the performance of EPR systems, and can potentially have a similar impact on DNP-NMR. The Phase I research achieved all of the proposal goals, including the demonstration of a more powerful 263 GHz source that was demonstrated to achieve significant DNP signal enhancement. The Phase II effort will build on this success in three ways; (i) the power level of the 263 GHz source will be further increased to facilitate a greater range of measurements, (ii) the technology will be extended to other frequencies of importance for EPR and DNP, specifically 395 and 527 GHz, (ii) the new sources will incorporate fast pulse capability as well as frequency and phase modulation, and (iv) the 263 GHz source will be developed to ensure easier operation by researchers who are not experts in millimeter wave technology; thereby accelerating the path to Phase III commercialization of this important technology.