The Millimeter-Wave Spectrum of Doubly Deuterated Propylene Oxide CH$_3$CHCD$_2$O

TL;DR

This study reports the millimeter-wave spectra of doubly deuterated propylene oxide, deriving molecular parameters and providing line lists to aid astrophysical searches and understanding of chiral molecules with internal motions.

Contribution

The paper presents the first detailed spectral analysis of doubly deuterated propylene oxide, including molecular parameters and line lists, combining experimental data with quantum chemical calculations.

Findings

Derived molecular parameters and tunneling constants.

Provided accurate line lists for astrophysical detection.

Compared experimental V3 barrier height with previous data.

Abstract

Spectra of doubly deuterated propylene oxide, CH$_3$CHCD$_2$O, were recorded in the millimeter-wave spectral region up to 330 GHz utilizing a 2f frequency modulated Terahertz spectrometer. Rotational and centrifugal distortion constants and tunneling parameters for the description of the internal rotation of the methyl group were retrieved. The software XIAM was used to describe the A-E tunneling splitting with a frequency uncertainty of 82 kHz. Molecular parameters derived from our measurements are complemented by quantum chemical anharmonic frequency calculations on the B3LYP/augcc-pVTZ level of theory. In addition, the barrier height to internal rotation of the methyl group,V3, was derived experimentally and found to slightly differ from the value reported for the main isotopologue. In view of astrophysical observations we provide accurate line lists to search for doubly deuterated propylene oxide in space. Furthermore, we deliver improved molecular parameters to further investigate the properties of a simple chiral molecule possessing internal large amplitude motions.