MRI: Development of Angle-Resolved Light Scattering System for Ultrafast Surface Spectroscopy

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This award from the Major Research Instrumentation program and the EPSCoR program supports the development of a state-of-the-art time- and angle-resolved hemispherical elastic light scattering (TARHELS) instrument to observe light scattering with femtosecond resolution at cryogenic temperatures. The apparatus will be the first optical system of this kind, and provides unique capabilities beyond current limitations and will advance the standards for state-of-the-art instrumentation in a field at the forefront of condensed matter research. Multi-user access to the instrument will significantly increase and advance the research activity of the Physics Department at the University of Puerto Rico-Mayaguez. Beyond its scientific impact, the project provides an excellent education and training opportunity for graduate students at the University of Puerto Rico, a higher education institution that serves and graduates the largest number of Hispanic STEM students in the United States. Students will receive extensive training in working with the modern ultrafast diffraction techniques that are frequently utilized in National Labs and the US industry.This TARHELS instrument will provide unique possibilities for the ultrafast pump-probe surface spectroscopy of condensed matter, while enabling high-quality recording and spectral analysis of hemispherical scattering indicatrix with femtosecond resolution using large-scale aspherical reflective optics. The setup is designed as a computer-controlled apparatus that operates with external ultrafast laser pulse sources. The use of several geometries will enable monitoring of the light scattering of homogenous and surface waves. The project will also develop the user interface and algorithms for fast analysis of the scattering field. Collecting the time- and angle-resolved scattering over a hemisphere, the TARHELS instrument will provide the real-time reconstruction and visualization of transient autocorrelation function and power spectral density of the surface, enabling insight into the nonsteady state of multi-scale structural irregularities. Operating at low temperatures, the TARHELS system will yield substantially new information about nonequilibrium disorder of stochastic surfaces on the mesoscale, information about grain-size-dependent electron-lattice interactions, the role of electronic correlations in nonequilibrium quantum phases of matter, and multi-scale quantum condensed matter dynamics, including insulator-to-metal phase transition in different functional materials, correlated oxides, topological insulators and superconductors under strong laser excitation.