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Title: A Capillary Absorption Spectrometer for Stable Carbon Isotope Ratio (13C/12C) Analysis in Very Small Samples

Abstract

A capillary absorption spectrometer (CAS) suitable for IR laser isotope analysis of small CO{sub 2} samples is presented. The system employs a continuous-wave (cw) quantum cascade laser to study nearly adjacent rovibrational transitions of different isotopologues of CO{sub 2} near 2307 cm{sup -1} (4.34 {mu}m). This initial CAS system can achieve relative isotopic precision of about 10 ppm {sup 13}C, or {approx}1{per_thousand} (per mil in delta notation relative to Vienna Pee Dee Belemnite) with 20-100 picomoles of entrained sample within the hollow waveguide for CO{sub 2} concentrations {approx}400 to 750 ppm. Isotopic analyses of such gas fills in a 1-mm ID hollow waveguide of 0.8 m overall physical path length can be carried out down to {approx}2 Torr. Overall {sup 13}C/{sup 12}C ratios can be calibrated to {approx}2{per_thousand} accuracy with diluted CO{sub 2} standards. A novel, low-cost method to reduce cw-fringing noise resulting from multipath distortions in the hollow waveguide is presented, which allows weak absorbance features to be studied at the few ppm level (peak-to-rms) after 1,000 scans are co-added in {approx}10 sec. The CAS is meant to work directly with converted CO{sub 2} samples from a Laser Ablation-Catalytic-Combustion (LA CC) micro-sampler to provide {sup 13}C/{sup 12}C ratios ofmore » small biological isolates with spatial resolutions {approx}50 {mu}m.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1035412
Report Number(s):
PNNL-SA-81307
Journal ID: ISSN 0034-6748; RSINAK; KP1704020; TRN: US201204%%583
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 83; Journal Issue: 2
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION; ABSORPTION; ACCURACY; CARBON ISOTOPES; LASERS; SPATIAL RESOLUTION; SPECTROMETERS; WAVEGUIDES

Citation Formats

Kelly, James F., Sams, Robert L., Blake, Thomas A., Newburn, Matthew K., Moran, James J., Alexander, M. L., and Kreuzer, Helen W. A Capillary Absorption Spectrometer for Stable Carbon Isotope Ratio (13C/12C) Analysis in Very Small Samples. United States: N. p., 2012. Web. doi:10.1063/1.3680593.
Kelly, James F., Sams, Robert L., Blake, Thomas A., Newburn, Matthew K., Moran, James J., Alexander, M. L., & Kreuzer, Helen W. A Capillary Absorption Spectrometer for Stable Carbon Isotope Ratio (13C/12C) Analysis in Very Small Samples. United States. doi:10.1063/1.3680593.
Kelly, James F., Sams, Robert L., Blake, Thomas A., Newburn, Matthew K., Moran, James J., Alexander, M. L., and Kreuzer, Helen W. Mon . "A Capillary Absorption Spectrometer for Stable Carbon Isotope Ratio (13C/12C) Analysis in Very Small Samples". United States. doi:10.1063/1.3680593.
@article{osti_1035412,
title = {A Capillary Absorption Spectrometer for Stable Carbon Isotope Ratio (13C/12C) Analysis in Very Small Samples},
author = {Kelly, James F. and Sams, Robert L. and Blake, Thomas A. and Newburn, Matthew K. and Moran, James J. and Alexander, M. L. and Kreuzer, Helen W.},
abstractNote = {A capillary absorption spectrometer (CAS) suitable for IR laser isotope analysis of small CO{sub 2} samples is presented. The system employs a continuous-wave (cw) quantum cascade laser to study nearly adjacent rovibrational transitions of different isotopologues of CO{sub 2} near 2307 cm{sup -1} (4.34 {mu}m). This initial CAS system can achieve relative isotopic precision of about 10 ppm {sup 13}C, or {approx}1{per_thousand} (per mil in delta notation relative to Vienna Pee Dee Belemnite) with 20-100 picomoles of entrained sample within the hollow waveguide for CO{sub 2} concentrations {approx}400 to 750 ppm. Isotopic analyses of such gas fills in a 1-mm ID hollow waveguide of 0.8 m overall physical path length can be carried out down to {approx}2 Torr. Overall {sup 13}C/{sup 12}C ratios can be calibrated to {approx}2{per_thousand} accuracy with diluted CO{sub 2} standards. A novel, low-cost method to reduce cw-fringing noise resulting from multipath distortions in the hollow waveguide is presented, which allows weak absorbance features to be studied at the few ppm level (peak-to-rms) after 1,000 scans are co-added in {approx}10 sec. The CAS is meant to work directly with converted CO{sub 2} samples from a Laser Ablation-Catalytic-Combustion (LA CC) micro-sampler to provide {sup 13}C/{sup 12}C ratios of small biological isolates with spatial resolutions {approx}50 {mu}m.},
doi = {10.1063/1.3680593},
journal = {Review of Scientific Instruments},
number = 2,
volume = 83,
place = {United States},
year = {Mon Feb 06 00:00:00 EST 2012},
month = {Mon Feb 06 00:00:00 EST 2012}
}