Communication: Evidence of stable van der Waals CO2 clusters relevant to Venus atmosphere conditions

Abstract

Non-intrusive spectroscopic probing of weakly bound van der Waals complexes forming in gaseous carbon dioxide is generally performed at low pressures, for instance in supersonic jets, where the low temperature favors dimers, or in few-atmosphere samples, where the signature of dimers varying as the squared gas density is entangled with the dominating collision-induced absorption. We report experimental and theoretical results on CO2 dimers at very high pressures approaching the liquid phase. We observe that the shape of the CO2-dimer bands undergoes a distinctive line-mixing transformation, which reveals an unexpected stability of the dimers despite the collisions with the surrounding particles and negates the common belief that CO2 dimers are short-lived complexes. Our results furnish a deeper insight allowing a better modeling of CO2-rich atmospheres and provide also a new spectroscopic tool for studying the robustness of molecular clusters.

CO2 Ocean Bistability on Terrestrial Exoplanets

“…Here, we propose a potential method for distinguishing between CO 2 condensing and non‐condensing worlds and, more generally, constraining the p CO 2 of a given exoplanet. This proposal is based on the tendency of CO 2 to dimerize and form molecular complexes at high pressures and low temperatures like those that occur in the CO 2 condensing atmospheres explored in this paper (Asfin et al., 2015 ; Leckenby & Robbins, 1966 ; Slanina et al., 1992 ; Tsintsarska & Huber, 2007 ). Similar to a method proposed for constraining O 2 partial pressure using spectroscopic O 2 dimer features in exoplanet observations (Misra et al., 2014 ), we suggest that high resolution spectroscopy from astronomical surveys may be able to detect CO 2 dimer features on high‐ p CO 2 exoplanets.…”

“…Consequently, it may be possible to discriminate between CO 2 ‐condensing and non‐CO 2 ‐condensing atmospheres using the presence or absence of CO 2 dimer features. These features have been detected in the near‐ and mid‐infrared around 3,700 cm −1 (2.7 μm) (Jucks et al., 1987 , 1988 ; Moazzen‐Ahmadi & McKellar, 2013 ), 2,350 cm −1 (4.3 μm) (Dehghany et al., 2010 ; Walsh et al., 1987 ), and 1,250–1,400 cm −1 (7.1–8.0 μm) (Asfin et al., 2015 ; Baranov et al., 2004 ), placing the features within the proposed wavelength range of future telescope architectures like the Large Interferometer For Exoplanets (Dannert et al., 2022 ; Quanz, Absil, et al., 2021 ; Quanz, Ottiger, et al., 2021 ). Fox and Kim ( 1988 ) note the possibility of detection of CO 2 dimers in the atmospheres of Mars and Venus, where they are suggested to exist at parts‐per‐thousand mole fractions, much lower than the expected dimer abundance in CO 2 condensing atmospheres due to the low pressure and high temperatures on Mars and Venus respectively.…”

Evaluation of spectral radiative properties of gases in high-pressure combustion

“…The shape of the continuum from collision-broadened lines implies that single lines decay more rapidly from the line centers, while transitioning to a more gradual decay in the far wing compared to self-broadened lines. This behavior could be related to long lived dimer interactions [23] .…”

Heterogeneous nucleation and growth of MOF crystals on polymer substrate to fabricate chitosan/ZIF-8 hydrogels for efficient capture of CO2

“…The adsorption capacity (q t ) of the samples for CO 2 was calculated by the van der Waals equation, and eqn ( 1) and ( 2) were used. 30 The n 0 and n t were calculated by substituting the corresponding P 0 and P t values into the equation, respectively:…”