Development of a quantum cascade laser absorption spectrometer for simultaneous measurement of 13C-18O and 18O-18O clumping in CO2.
Rapid Commun Mass Spectrom
; 38(16): e9836, 2024 Aug 30.
Article
in En
| MEDLINE
| ID: mdl-38887894
ABSTRACT
RATIONALE Dual clumped isotope paleothermometry determines carbonate formation temperatures by measuring the frequency of 13C-18O (∆638) and 18O-18O (∆828) pairs in carbonates. It resolves isotopic kinetic biases and thus enables more accurate paleotemperature reconstructions. However, high-precision measurements of 18O-18O clumping using current techniques requires large sample sizes and long acquisition times. METHODS:
We developed a mid-infrared isotope ratio laser spectrometer (IRLS) for simultaneous measurement of the isotopologue ratios ∆638 and ∆828 in gas-phase carbon dioxide (CO2) at room temperature. Our IRLS uses a single laser scanning from 2290.7 to 2291.1 cm-1 and a 31 m pathlength optical cell, and it simultaneously measures the five isotopologues required for calculating ∆638 and ∆828 16O12C16O, 16O13C16O, 16O12C18O, 16O13C18O, and 18O12C18O. In addition, our IRLS can measure 16O12C17O, enabling ∆17O analysis.RESULTS:
At ~20°C and a CO2 pressure of ~2 Torr, our IRLS system achieved precisions of 0.128 and 0.140 within 20 s for abundances of the clumped isotopologues 16O13C18O and 18O12C18O, respectively, and precisions of 0.267, 0.245, and 0.128 for 16O12C16O, 16O13C16O, and 16O12C18O. This yielded precisions of 0.348 (∆638) and 0.302 (∆828) within 25 s. Simulated sample-reference switching highlights the potential of our system and the need for further development.CONCLUSIONS:
We demonstrated simultaneous measurements of ∆638 and ∆828 in CO2 to precisions of <0.35 within 25 s using a room-temperature, single-laser IRLS. Future developments on better resolving 16O12C16O and 16O13C16O peaks and system temperature control could further improve the measurement precision.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
Rapid Commun Mass Spectrom
Year:
2024
Document type:
Article
Affiliation country:
United States
Country of publication:
United kingdom