Abstract
Abstract Hyperfine-resolved collisions between OH radicals and He atoms are investigated using quantum scattering calculations and the most recent ab initio potential energy surface, which explicitly takes into account the OH vibrational motion. Such collisions play an important role in astrophysics, in particular in the modelling of OH masers. The hyperfine-resolved collision cross sections are calculated for collision energies up to 2500 cm-1 from the nuclear spin free scattering S-matrices using a recoupling technique. The collisional hyperfine propensities observed are discussed. As expected, the results from our work suggest that there is a propensity for collisions with ΔF = Δj. The new OH−He hyperfine cross sections are expected to significantly help in the modelling of OH masers from current and future astronomical observations. Graphical abstract
Highlights
The most abundant nuclear constituents of interstellar molecules are H, C, O and N
Due to the nonzero nuclear spin, nuclear hyperfine splitting occurs in the rotational spectrum of molecules containing these nuclei, such as CN, HCN, NH3 or OH
For low-energy rotational excitation, we employ a new set of three-dimensional potential energy surfaces (PES) for the OH(X2Π)−He van der Waals system, which explicitly takes into account the OH vibrational motion
Summary
The most abundant nuclear constituents of interstellar molecules are H, C, O and N. Among these are the 14N and 1H nuclei which both have a non-zero nuclear spin with I = 1 and I = 1/2, respectively. Due to the nonzero nuclear spin, nuclear hyperfine splitting occurs in the rotational spectrum of molecules containing these nuclei, such as CN, HCN, NH3 or OH. The hyperfine splitting is generally very small but it is well resolved in various emission spectra from molecular clouds, in particular from cold dense molecular clouds [1]. Resolving the hyperfine structure of a rotational transition is extremely useful. The abundance of the molecule can be directly derived from the fit The abundance of the molecule can be directly derived from the fit (e.g. [2])
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
