Abstract
High Resolution Image Download MS PowerPoint Slide This study investigates the formation of carbon dioxide clathrate hydrates under conditions simulating interstellar environments, a process of significant astrophysical and industrial relevance. Clathrate hydrates, where gas molecules are trapped within water ice cages, play an essential role in both carbon sequestration strategies and understanding of the behavior of ices in space. We employed a combination of Fourier Transform Infrared (FTIR) spectroscopy, mass spectrometry, temperature-programmed desorption (TPD), and Density Functional Theory (DFT) calculations to explore thin films of H 2 O:CO 2 ice mixtures with varying CO 2 concentrations (5–75%) prepared by vapor deposition at temperatures ranging between 11 and 180 K. The study revealed the influence of CO 2 concentration and deposition temperature on the formation mechanism of diverse structures, including clathrate hydrates, polyaggregates, and segregated CO 2 groups. Spectral features associated with CO 2 encapsulation in clathrate hydrates were observed at 2335, 2349, and 3698 cm –1 in the 5 and 15% mixtures after deposition at 11 K and after warming at temperatures above 100 K. The observed increase in CO 2 sublimation temperature to 145–155 K and co-condensation of CO 2 molecules at 172 K with water molecules at a pressure of 0.5 μTorr can be attributed to the encapsulation of CO 2 molecules within the robust hydrogen-bonded framework of the clathrate cages under specific conditions. These findings enhance our understanding of the intricate processes involved in clathrate and hydrate formation in CO 2 and H 2 O mixtures, shedding light on their physical properties and the dependence of their specific characteristics on the formation method.