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1. InChI isotopologue and isotopomer specifications

   https://doi.org/10.1186/s13321-024-00847-8  

   Moseley, Hunter N. B.; Rocca-Serra, Philippe; Salek, Reza M.; Arita, Masanori; Schymanski, Emma L. (May 2024, Journal of Cheminformatics)

   AbstractThis work presents a proposed extension to the International Union of Pure and Applied Chemistry (IUPAC) International Chemical Identifier (InChI) standard that allows the representation of isotopically-resolved chemical entities at varying levels of ambiguity in isotope location. This extension includes an improved interpretation of the current isotopic layer within the InChI standard and a new isotopologue layer specification for representing chemical intensities with ambiguous isotope localization. Both improvements support the unique isotopically-resolved chemical identification of features detected and measured in analytical instrumentation, specifically nuclear magnetic resonance and mass spectrometry. Scientific contributionThis new extension to the InChI standard would enable improved annotation of analytical datasets characterizing chemical entities, supporting the FAIR (Findable, Accessible, Interoperable, and Reusable) guiding principles of data stewardship for chemical datasets, ultimately promoting Open Science in chemistry. 

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2. Isotopologue trace gas detection using multipass cavity Raman scattering

   https://doi.org/10.1364/CLEO_AT.2022.AM2M.3  

   Singh, Jaspreet; Muller, Andreas (May 2022, Conference on Lasers and Electro-Optics: Applications and Technology 2022)

   Feedback-assisted multipass-cavity spontaneous Raman scattering is demonstrated as an effective method of isotopologue analysis. Deuterium concentration precision near one part-per-million in water was obtained by direct vapor and indirect dihydrogen measurements. 

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3. Mapping Protoplanetary Disk Vertical Structure with CO Isotopologue Line Emission

   https://doi.org/10.3847/1538-4357/acb3c4  

   Law, Charles_J; Teague, Richard; Öberg, Karin_I; Rich, Evan_A; Andrews, Sean_M; Bae, Jaehan; Benisty, Myriam; Facchini, Stefano; Flaherty, Kevin; Isella, Andrea; et al (May 2023, The Astrophysical Journal)

   Abstract High-spatial-resolution observations of CO isotopologue line emission in protoplanetary disks at mid-inclinations (≈30°–75°) allow us to characterize the gas structure in detail, including radial and vertical substructures, emission surface heights and their dependencies on source characteristics, and disk temperature profiles. By combining observations of a suite of CO isotopologues, we can map the two-dimensional (r,z) disk structure from the disk upper atmosphere, as traced by CO, to near the midplane, as probed by less abundant isotopologues. Here, we present high-angular-resolution (≲0.″1 to ≈0.″2; ≈15–30 au) observations of CO,¹³CO, and C¹⁸O in either or bothJ= 2–1 andJ= 3–2 lines in the transition disks around DM Tau, Sz 91, LkCa 15, and HD 34282. We derived line emission surfaces in CO for all disks and in¹³CO for the DM Tau and LkCa 15 disks. With these observations, we do not resolve the vertical structure of C¹⁸O in any disk, which is instead consistent with C¹⁸O emission originating from the midplane. Both theJ= 2–1 andJ= 3–2 lines show similar heights. Using the derived emission surfaces, we computed radial and vertical gas temperature distributions for each disk, including empirical temperature models for the DM Tau and LkCa 15 disks. After combining our sample with literature sources, we find that¹³CO line emitting heights are also tentatively linked with source characteristics, e.g., stellar host mass, gas temperature, disk size, and show steeper trends than seen in CO emission surfaces. 

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4. Clumped isotopologue fractionation by microbial cultures performing the anaerobic oxidation of methane

   https://doi.org/10.1016/j.gca.2020.10.015  

   Ono, Shuhei; Rhim, Jeemin H.; Gruen, Danielle S.; Taubner, Heidi; Kölling, Martin; Wegener, Gunter (January 2021, Geochimica et Cosmochimica Acta)

   null (Ed.)
5. Deperturbation analysis of the A1Π(v = 2) level in the 12C18O isotopologue

   https://doi.org/10.1016/j.jqsrt.2021.107837  

   Malicka, M.I.; Ryzner, S.; Heays, A.N.; de Oliveira, N.; Field, R.W.; Ubachs, W.; Hakalla, R. (July 2021, Journal of Quantitative Spectroscopy and Radiative Transfer)

   null (Ed.)