The Rotational Spectrum of 1-cyanocyclopentene and Its Search towards TMC-1
Name
Mato_2025_ApJ_994_217.pdf
Description
Published version
Size
1.36 MB
Format
Adobe PDF
Checksum (MD5)
775dc94fa44b2cf7a4e5057e843663e4
Author(s)
Mato, Sergio
Cernicharo, José
León, Iker
McGuire, Brett A
Alonso, Elena R
Date Issued
November 27, 2025
Journal
The Astrophysical Journal
Publisher
American Astronomical Society
Citation
Sergio Mato et al 2025 ApJ 994 217
Version
Final published version
Abstract
The astronomical detection of CN-functionalized ring molecules in TMC-1 has opened a new and unexplored area in space-based aromatic organic chemistry. The rotational spectrum of 1-cyano-cyclopentene (1-CNCPE) has been investigated using a combination of low- and high-resolution microwave spectroscopy techniques under jet-cooled and room temperature conditions. A Stark-modulated low-resolution spectrum revealed a clear a-type R-branch band structure, indicative of a single dominant rotamer with prolate character. High-resolution spectra recorded with broadband (CP-FTMW) and narrowband (MB-FTMW) techniques exhibited a doubling of transitions, attributed to tunneling between two ring-puckering vibrational substates, denoted 0+ and 0−. In addition, the millimeter-wave spectrum in the 329–394 GHz region has also been analyzed. Due to strong coupling between these levels, the spectral analysis required a Hamiltonian including Coriolis interaction terms within the reduced axis system formalism. This approach enabled the successful assignment and fitting of over 1244 rotational transitions, including hyperfine structure from the 14N nucleus and weak b- and c-type lines. The final spectroscopic parameters provide a reliable basis for astrophysical searches, and partition functions are reported at standard temperatures. We have searched for this species toward TMC-1 using the data of the QUIJOTE line survey. Only a 3σ upper limit to the column density of 3 × 1010 cm−2 has been obtained. Using the available spectroscopic data, we also searched for the two axial and equatorial conformers of 3-cyanocyclopentene, establishing an upper limit similar to that of 1-CNCPE.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
Terms of Use
Creative Commons Attribution
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.3847/1538-4357/ae1ba1
