A High-Resolution Rotational Analysis of 2‑Chloroethanol (HOCH₂CH₂Cl) and Its First Vibrationally Excited State.
7 affiliations
- 1Department of Chemistry, University of Wisconsin-madison, Madison, Wisconsin 53706, United States.
- 2Department of Chemistry, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States.
- 3Department of Chemistry, New College of Florida, Sarasota, Florida 34243, United States.
- 4BrightSpec, Inc., 770 Harris St., Suite 104b, Charlottesville, Virginia 22903-4583, United States.
- 5Canadian Light Source. Inc., University of Saskatchewan institution, Saskatoon, Saskatchewan S7N 2 V3, Canada.
- 6Niels Bohr Institute, University of Copenhagen, Jagtvej 155A, Copenhagen N., Copenhagen DK-2200, Denmark.
- 7Department of Astronomy, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States.
Abstract
An extensive analysis of the high-resolution rotational spectrum (8-26 GHz, 140-700 GHz, 100-600 cm⁻¹) of the simplest stable chlorohydrin, 2-chloroethanol, is provided by combining high-resolution infrared, microwave, and millimeter-wave spectra. The ground state and first vibrationally excited state of both chlorine isotopologues (HOCH₂CH₂ ³⁵Cl and HOCH₂CH₂ ³⁷Cl) are well treated using a single-state distorted rotor Hamiltonian in the A reduction and I r representation, reporting up to a full set of octic distortion constants. The extended microwave spectrum collected and the well-resolved quadrupole splitting observed therein allowed for the further refinement of quadrupole coupling parameters. Inclusion of rotationally resolved infrared transitions enabled the accurate and precise determination of the vibrational band origin of ν₂₁ for HOCH₂CH₂ ³⁵Cl (150.908 599 5 (43) cm⁻¹). The high spectral density made measurement and least-squares fitting of transitions in both rotational and high-resolution infrared spectra challenging and is the likely source of the larger-than-expected σfit value of up to 0.060 MHz for each fit. Nevertheless, the extended millimeter-wave spectrum reported here provides spectral frequencies that directly overlap with astronomical data, allowing for a more thorough search for this species in the interstellar medium. Despite its expected formation from HCl with either oxirane or ethylene glycol in the interstellar medium, 2-chloroethanol continues to evade detection. We report upper limits on the column density toward 30 astrophysically diverse regions. The reported upper limits do not provide significant new constraints on the chemistry of this species in the interstellar medium and highlight the limited knowledge of interstellar chlorine chemistry.
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BibTeX
@article{bunn2026highresolution,
title = {{A High-Resolution Rotational Analysis of 2‑Chloroethanol (HOCH₂CH₂Cl) and Its First Vibrationally Excited State.}},
author = {Hayley A Bunn and Holdson H Liang and Brian J Esselman and Paul L Raston and Andi Pracko and Steven Shipman and Brant Billinghurst and Jianbao Zhao and Jes K Jørgensen and Susanna L Widicus Weaver},
journal = {ACS earth \& space chemistry},
year = {2026},
month = sep,
doi = {10.1021/acsearthspacechem.6c00221},
url = {https://europepmc.org/article/MED/42898814},
note = {CC BY},
}
RIS
TY - JOUR
TI - A High-Resolution Rotational Analysis of 2‑Chloroethanol (HOCH₂CH₂Cl) and Its First Vibrationally Excited State.
AU - Hayley A Bunn
AU - Holdson H Liang
AU - Brian J Esselman
AU - Paul L Raston
AU - Andi Pracko
AU - Steven Shipman
AU - Brant Billinghurst
AU - Jianbao Zhao
AU - Jes K Jørgensen
AU - Susanna L Widicus Weaver
PY - 2026
DA - 2026/09/21
JO - ACS earth & space chemistry
DO - 10.1021/acsearthspacechem.6c00221
UR - https://europepmc.org/article/MED/42898814
AB - An extensive analysis of the high-resolution rotational spectrum (8-26 GHz, 140-700 GHz, 100-600 cm⁻¹) of the simplest stable chlorohydrin, 2-chloroethanol, is provided by combining high-resolution infrared, microwave, and millimeter-wave spectra. The ground state and first vibrationally excited state of both chlorine isotopologues (HOCH₂CH₂ ³⁵Cl and HOCH₂CH₂ ³⁷Cl) are well treated using a single-state distorted rotor Hamiltonian in the A reduction and I r representation, reporting up to a full set of octic distortion constants. The extended microwave spectrum collected and the well-resolved quadrupole splitting observed therein allowed for the further refinement of quadrupole coupling parameters. Inclusion of rotationally resolved infrared transitions enabled the accurate and precise determination of the vibrational band origin of ν₂₁ for HOCH₂CH₂ ³⁵Cl (150.908 599 5 (43) cm⁻¹). The high spectral density made measurement and least-squares fitting of transitions in both rotational and high-resolution infrared spectra challenging and is the likely source of the larger-than-expected σfit value of up to 0.060 MHz for each fit. Nevertheless, the extended millimeter-wave spectrum reported here provides spectral frequencies that directly overlap with astronomical data, allowing for a more thorough search for this species in the interstellar medium. Despite its expected formation from HCl with either oxirane or ethylene glycol in the interstellar medium, 2-chloroethanol continues to evade detection. We report upper limits on the column density toward 30 astrophysically diverse regions. The reported upper limits do not provide significant new constraints on the chemistry of this species in the interstellar medium and highlight the limited knowledge of interstellar chlorine chemistry.
SN - 2472-3452
ER -