The noble gas geochemistry lab was established at OSU through support from a Major Research Instrumentation proposal (PIs Graham, Brook, Duncan and Lupton). This project was funded by the Marine Geology & Geophysics program in NSF\u2019s\u00a0 Division of Ocean Sciences. The primary instrumentation is a noble gas mass spectrometer purchased from Nu Instruments and installed in 2008. Other major lab components include a high-temperature vacuum furnace, and an on-line crushing system, for the extraction of gases from (primarily solid) terrestrial materials. <\/p>\n\n\n\n
We have the ability to perform noble gas isotope analyses at\na very low level in rocks and minerals, comparable in analytical precision,\naccuracy and detection limit to the best noble gas labs in the world. The noble gases (helium,\nneon, argon, krypton, xenon and radon) are unique for their utility in\naddressing fundamental questions about the history and dynamics of Earth\nsystems. The range of potential scientific applications is very broad and\nincludes many fields of interest to geoscientists, including the origin and\nevolution the atmosphere and oceans, hydrothermal processes, formation of ore\ndeposits, earthquake\/volcanic hazard assessment, ocean circulation, the flux of\ncosmic dust to the Earth, air-sea gas exchange, surface exposure dating of\nrocks and sediments, erosion rates and landscape evolution, thermochronology\nand tectonic uplift of mountain belts, groundwater dating, radionuclide\ntransport and fallout, and nuclear waste disposal. Work carried out in the OSU\nlab since the first measurements began in 2011 have primarily used high\nprecision analyses of helium isotopes in rocks from mid-ocean ridges, ocean\nislands and continental rifts to study the chemical geodynamics of the solid\nEarth, evolution of volcanic systems, and volcanic degassing.<\/p>\n\n\n\n
The\nlab operations are supervised by David Graham. Graham guides graduate student\nand outside vistor work carried out in the lab, including interpretation and\npublication of the analytical results. He\ndevotes a major proportion of his time to overseeing, maintaining and\ndeveloping the lab instrumentation. During normal operation, the lab runs 24\nhours a day, but it is monitored remotely by Graham during those nights and\nweekends. <\/p>\n\n\n\n The noble gas mass spectrometer<\/strong> is a low volume instrument operated under static vacuum, and has a high sensitivity ion source (Nier-type). Typical sensitivity is 0.23 mA torr-1<\/sup> for 4<\/sup>He and 1.7 mA torr-1<\/sup> for 40<\/sup>Ar at 400 mA. The instrument is all-metal construction and can be baked to reach low background levels and low static gas rise rates, particularly important for the isotope analysis of small amounts of noble gases. The OSU Noblesse instrument is fitted with a single faraday cup and 3 ion counting detectors. The high mass ion counter position is shared with the faraday with switching via an electrostatic deflector. The central and low mass ion counting detectors have a special filter to eliminate scattered, low energy ions that may interfere with small ion beams (especially important when trying to measure very small amounts of 3<\/sup>He in the presence of large amounts of 4<\/sup>He, for example). The Noblesse is a variable dispersion instrument employing patented, electrostatic \u201czoom optics\u201d derived from the Nu Plasma ICP-MS. It performs the 3<\/sup>He\/4<\/sup>He measurement in a pseudo high-resolution mode that partially resolves 3<\/sup>He from HD+<\/sup>+H3<\/sub>+<\/sup>, but any tailing from the HD+<\/sup>+H3<\/sub>+<\/sup> beneath the peak-flat where 3<\/sup>He is measured is virtually absent. The instrument also allows simultaneous collection of 20<\/sup>Ne, 21<\/sup>Ne and 22<\/sup>Ne, and rapid peak switching to measure 40<\/sup>Ar+<\/sup> and CO2<\/sub>+<\/sup> during the Ne analysis to monitor potential contributions of doubly charged interfering species. 36<\/sup>Ar, 38<\/sup>Ar and 40<\/sup>Ar can be measured simultaneously, with a choice between ion counting or faraday detection for the 40<\/sup>Ar peak depending upon sample size. Kr and Xe isotopes can be measured via peak jumping. <\/p>\n\n\n\n The gas extraction\nline<\/strong> has a computer-controlled sample processing and introduction system\nconnected to the mass spec inlet. This consists of a Janis cryogenic cold trap\nfor routine separation of the noble gases (cryostat temperature control to ~8\n\u00b0K is maintained by a closed-loop compressor), air-actuated pneumatic valves,\nheated SAES getters, pressure sensors, and oil-free vacuum pumps\n(turbomolecular, scroll and ion) to minimize hydrocarbons. Air and specialized\ngas standards are automatically pipetted in known quantity (0.1 cm3<\/sup>)\nfor routine calibration of the mass spectrometer. <\/p>\n\n\n\n The high-temperature vacuum furnace <\/strong>\u00a0is used for melting and step-heating of rocks, minerals and sediments. <\/strong>It has a tantalum resistive heating element and a central Ta crucible. This is surrounded by a series of heat shields and the whole assembly is contained in a water cooled chamber which is independently pumped from the main vacuum line (via a diffusion pump with a backing rotary pump). Cooling is maintained by a dedicated water chiller having a minimum flow rate of 2 l min-1<\/sup>. The pressure of the secondary vacuum is monitored using a Penning gauge and furnace power is interlocked to this measurement and the chiller water flow. A disposable Ta liner contains samples dropped into the furnace and minimizes chemical reaction with the crucible walls. Samples are introduced by a low volume carousel that allows up to 12 samples to be loaded under vacuum simultaneously. A viewport enables the viewing of samples during heating, as well as monitoring the crucible temperature independently with an optical pyrometer if desired. The temperature of the furnace is monitored with a W\/W-Re thermocouple and controlled using a dedicated controller interfaced to a computer. Different heating profiles may be stored for use in different experiments. <\/p>\n\n\n\n The sample processing line also includes a stainless steel rock crushing manifold<\/strong>, for in vacuo <\/em>crushing of rock and mineral samples to release gases from fluid and melt inclusions. <\/p>\n\n\n\n Welcome to the new Oregon State University Noble Gas Laboratory website. The site is currently under construction and we appreciate your patience. The noble gas geochemistry lab was established at OSU through support from a Major Research Instrumentation proposal (PIs Graham, Brook, Duncan and Lupton). This project was funded by the Marine Geology & Geophysics … Continue reading The Facility<\/span> ![\"\"](\"https:\/\/osu-wams-blogs-uploads.s3.amazonaws.com\/blogs.dir\/3568\/files\/2019\/11\/homepic1-1.jpg\")
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