Bright Quantum Dot Scintillator for High Frame Rate Imaging

Recent significant improvements in synchrotron radiation sources have enabled the growth of powerful techniques such as time-resolved X-ray diffraction studies for use in understanding dynamic phenomena in materials, including those in biological systems. To make the most effective use of synchrotron sources for protein and other such studies, however, new, efficient, high-throughput detectors are needed that will enhance the quality of the molecular model that is the end product of the macromolecular crystallography process. Novel detectors based on new designs of charge coupled devices (CCDs) have been developed, but the performance of these powerful devices is significantly limited by all current X-ray-to-light converters that provide low light, low X-ray absorption, and a tradeoff between spatial resolution and efficiency. To address these issues, we are developing a novel semiconductor quantum dot scintillator that promises to provide bright emissions, high X-ray absorption, and fast decay with no afterglow, emission in the wavelength range most suitable for CCD-type devices, and orders-of-magnitude higher radiation resistance compared to current scintillators. This scintillator will be fabricated in a thin film form, which, in addition to its excellent scintillation properties, will provide very high spatial resolution. When combined with a suitable readout, this scintillator will enable realization of a cost-effective high frame rate, large area, high resolution detector needed for many important time-resolved X-ray diffraction and other studies. The Phase I research accomplished, and in many respects exceeded, all stated goals, and as such successfully demonstrated the feasibility of developing novel scintillators based on quantum dot nanoparticles. Through our inventions of new technologies to synthesize quantum dots and incorporate them in suitable polymer matrices, our Phase I research succeeded in demonstrating the first ever X-ray imaging by means of quantum dot scintillators using both X-ray generators at RMD synchrotron sources. Highly encouraging Phase I results led us and our collaborators, to develop a comprehensive research plan for the Phase II and subsequent commercialization of the technology. Our Phase II research will focus on modifying quantum dot structural and morphological properties to further enhance X-ray absorption efficiency, decay times, and emission efficiency, and amplify Stokes shift to minimize re-absorption. Complementary developments in the medium in which quantum dots will be suspended will also be undertaken, with a goal of creating meta-particle structures for improved charge transport, and hence emission efficiency, and enhanced X-ray absorption. These parallel approaches will lead to the desired scintillator film fabrication and to experimental evaluations at Argonne National Laboratory and to substantial efforts toward commercialization of this technology. Commercial applications and other benefits as described by the awardee: The technology proposed here is of critical importance in many important synchrotron-based applications, including time-resolved macromolecular crystallography and polymer research and other applications ranging from medical imaging to nondestructive testing. Due to its potential applications in homeland security and advanced biotechnology, National Security Technologies, LLC has become highly enthusiastic of the proposed research