Phosphor materials are currently being utilized in a wide variety of applications. The requirements for phosphors have become more and more stringent with smaller and smaller particles being required. In the Phase I program, UES Inc. in collaboration with Penn State University has demonstrated the feasibility of a few approaches for high rate production of high efficiency IR to IR up-converting nanoparticles. The objective of Phase II STTR is to continue refinement and optimization of the technology developed in Phase I with emphasis on emission strength, environmental stability, and process scalability. BENEFIT: Successful completion of the program will provide a commercially viable approach to produce IR to IR up-converting nanoparticles. Military application involves tagging and tracking of assets, identifying friend or foe, and for use in identifying disturbed soil in perimeter security. Commercial applications include fluorescence optical imaging for biomedical applications.