Ruby Fluorescence Spectroscopy

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Garai, Máté
DiNella, Vincent
Thompson, Dr. Lily
Abdelhamid, Alaa
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Scholarship Sewanee 2022 , University of the South , Ruby , diamond , fluorescence , spectroscopy , high-pressure , mineral physics , Raman
The interiors of terrestrial planets, satellites, and other celestial bodies may provide essential clues to a better understanding of the formation and evolution of our Solar System and other planetary systems throughout the galaxy. Mineral physics is a scientific discipline that probes the physical and chemical properties of planet-forming materials at the extreme pressure and temperature conditions of planetary interiors. For example, the pressure at the center of the Earth is 3.6 million times atmospheric pressure and the temperature of the Earth’s core is approximately the same temperature as the surface of our sun. The pressures and temperatures inside larger or denser planets and exoplanets are even more extreme. In order to constrain the formation, composition, and evolution of planetary interiors, we must first understand what happens to planet-forming materials at the pressure and temperature conditions where we expect them to exist. Mineral physicists can reproduce the high pressures of planetary interiors using diamond anvil cells (DACs), which can be combined with lasers or external resistive heating to recreate the extreme temperatures of planetary interiors. To measure and monitor the pressure of samples that are pressurized within a DAC, an in situ pressure standard is required. Ruby (chromium-doped Al2O3 or Cr:Al2O3) is used as an in situ pressure standard because of two important properties: (1) it fluoresces at a well-defined wavelength of light when excited by a laser, and (2) the wavelength of the ruby fluorescence increases as the ruby is pressurized in a way that has been well-calibrated. In the summer of 2021, Mate Garai, Alaa Adel Abdelhamid, and Vincent DiNella worked under the supervision of Dr. Lily Thompson to design and construct a ruby fluorescence spectrometer that allows the in situ measurement of pressurized mineral physics experiments by exciting ruby fluorescence and measuring the resultant fluorescence spectra.