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Proceedings Paper

Hollow fiber mid-IR spectrometer with UV laser ablation sampling for fine spatial resolution of isotope ratios in solids
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Paper Abstract

We describe a system that combines isotope ratio analysis via mid-infrared (Mid-IR) laser absorption spectroscopy with fine spatial resolution sampling using a UV pulsed laser. The UV laser ablates a pit in a solid on the order of 10 microns in diameter. The sample-derived particulates resulting from laser ablation pass through a micro-combustor, and the resulting gas is analyzed using Mid-IR laser absorption spectroscopy in a capillary absorption spectrometer (CAS). The CAS uses a hollow fiber optic waveguide with a reflective inner coating and a small internal volume on the order of 1 ml. The hollow fiber both guides the laser light from source to detector and contains the gas sample at reduced pressure. Near unity overlap between the laser beam and sample enables sensitive analysis with ultra-small sample size. A prototype system has been demonstrated to enable stable carbon isotopic analysis (δ13C) with 1 per mil precision using < 1 picomole of carbon and is currently being used to study nutrient exchange in soil/root/microbial rhizosphere studies. The smaller sample size of this system is enabling fine spatial resolution analysis (on the order of 10 microns), which is roughly an order of magnitude smaller than was possible with an isotope ratio mass spectrometer (IRMS). In addition to rhizosphere studies, the system can provide a useful tool for fine scale isotope analysis with applications in biological, forensic, and environmental science.

Paper Details

Date Published: 31 January 2020
PDF: 7 pages
Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 112881Z (31 January 2020); doi: 10.1117/12.2546908
Show Author Affiliations
Jason Kriesel, Opto-Knowledge Systems, Inc. (United States)
Camille Makarem, Opto-Knowledge Systems, Inc. (United States)
Andrew Fahrland, Opto-Knowledge Systems, Inc. (United States)
James Moran, Pacific Northwest National Lab. (United States)
Timothy Linley, Pacific Northwest National Lab. (United States)
James Kelly, Opto-Knowledge Systems, Inc. (United States)

Published in SPIE Proceedings Vol. 11288:
Quantum Sensing and Nano Electronics and Photonics XVII
Manijeh Razeghi; Jay S. Lewis; Giti A. Khodaparast; Pedram Khalili, Editor(s)

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