This award will permit the upgrading of existing equipment in the mineral physics laboratory at UC Santa Cruz. This equipment will not only provide a state-of-the-art training ground for a broad group of graduate and undergraduate students, but will also ensure adherence to high-level laser safety protocols. The mineral physics laboratory at UCSC has an extended history of training students for placement in academia and industry who have expertise in the high-pressure spectroscopy of Earth materials, and this upgrade will allow this training to continue with more user- and safety-friendly equipment. In addition to safety upgrades of the UCSC pressure-measurement system, a new Raman spectrometer will be acquired that will replace a marginally functional and obsolete 18-year old apparatus with an instrument that has higher spatial resolutions, vastly improved detection technology, and modern instrument-control and data-collection software. The issues addressed by the research enabled by this upgrade include: the water and carbon storage capacity of the deep Earth, and how exchange of water and carbon takes place between the deep Earth and the surface environment, with relevance to the formation of Earth?s oceans; the structure and physical properties of melts and fluids at high pressures, with implications for issues ranging from explosive volcanic events generated via subduction-related processes, to the possible presence of partially melted zones near Earth?s core-mantle boundary that may represent the ?roots? of deeply-derived volcanic upwellings. This apparatus will be deployed for non-high pressure materials-characterization as well, including probing fine-grained archeological samples, and fluid inclusion and paleontologic studies. In essence, it will also function as a tool for rapid and fine-scale mineral and fluid characterization that will yield insights into phenomena as diverse as the firing temperatures of ancient ceramics, the degree (and type) of fossilization produced in different geologic environments, and the compositions of ore-forming fluids trapped in mineral hosts.
With this funding, a Horiba Jobin-Yvon Labram ‘Evolution’ micro-Raman spectrometer was acquired. The instrument will be used to collect data on the bonding environments of mineral, rocks and fluids, primarily to understand the role of pressure and temperature on the physical properties of earth and planetary materials. The micro-Raman spectrometer was installed at UCSC in February of 2013, and underwent final specification approvals in early April. In its first 2 months of operation, multiple research groups have utilized the instrument, including a geochronology group focused on characterizing the degree of radiation damage of zircons caused by natural radioactivity, and our own high-pressure group, which initially probed the high-pressure behavior of organic materials that have been found within meteorites, and the high-pressure polymorphism of sulfates. Work on carbonates, silicates and aqueous fluids is imminently planned. The micro-Raman instrument can deploy a range of excitation wavelengths, spanning from the green (532 nm) to the near infrared (785 nm); the optics of the instrument are also compatible with both our extant Ar-ion lasers (488 nm) and our Nd:YAG laser (1032 nm). Characteristic focal spot dimensions are approximately 1 micron using a 100x objective, and 2 microns using a 50 micron objective. As such, the instrument is optimized for both micro-characterization of heterogeneous samples (such as radiation damaged zircons and thin sections of rocks), and for probing high-pressure samples at spots characterized by minimal pressure gradients. The instrument can also readily conduct fluorescence measurements, as well: our primary application to date has been associated with the ruby fluorescence pressure measurement technique, but further fluorescent studies under pressure are also planned.
