Neutron Vibrational Spectroscopic Study of the 1:1 Acetylene:Ammonia Cocrystal Relevant to Titan, Saturn's Moon

Published

July 5, 2024

Author(s)

Morgan Kramer, Trump Benjamin, Luke Daemen, Rafael Balderas-Xicohtencatl, Yongqiang Cheng, Anibal J. Ramirez-Cuesta, Craig Brown, Tomce Runcevski

Abstract

The surface of Titan, Saturn's icy moon, is believed to be comprised of various molecular minerals with a great diversity in structure and composition. Under the surface conditions, 93 K and 1.45 atm, most small molecules solidify and form minerals, including acetylene and ammonia. These two compounds can form single-component solids but also a 1:1 bina-ry cocrystal that exhibits intriguing rotor phase behavior. This cocrystal is a putative mineral on Titan and other plane-tary bodies such as comets. In addition, the structure of the cocrystal is relevant to fundamental science as it can help better understand the emergence of rotor phases. Here we present a detailed vibrational neutron spectroscopic study sup-ported by neutron powder diffraction study on the cocrystal and the single-phase solids. The experimentally observed spectral bands were assigned based on theoretical calculations. The established spectra–properties correlations for the cocrystal corroborate the observed properties. To the best of our knowledge, this study presents the first example of the application of neutron vibrational spectroscopy in studying Titan-relevant organic minerals.

Citation

Journal of Physical Chemistry A

Volume

128

Issue

28

Pub Type

Journals

Download Paper

https://doi.org/10.1021/acs.jpca.4c02360

Local Download

Keywords

Cocrystals, Minerology, Organic crystals, spectroscopy, Neutron Vibrational Spectroscopy, Inelastic Neutron Scattering, Titan, Astrochemistry

Citation

Kramer, M. , Benjamin, T. , Daemen, L. , Balderas-Xicohtencatl, R. , Cheng, Y. , Ramirez-Cuesta, A. , Brown, C. and Runcevski, T. (2024), Neutron Vibrational Spectroscopic Study of the 1:1 Acetylene:Ammonia Cocrystal Relevant to Titan, Saturn's Moon, Journal of Physical Chemistry A, [online], https://doi.org/10.1021/acs.jpca.4c02360, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=957897 (Accessed October 9, 2025)