Identification of the D_3h Isomer of Carbon Trioxide (CO₃) and Its Implications for Atmospheric Chemistry

Abstract

The CO3 molecule is considered an important reaction intermediate in the atmospheres of Earth and Mars for quenching electronically excited oxygen atoms and in contributing to the anomalous 18O isotope enrichment. The geometry of the CO3 intermediate plays an important role in explaining these effects; however, only the cyclic (C(2v)) isomer has been experimentally confirmed so far. Here, we report on the first spectroscopic detection of the acyclic (D(3h)) isomer of carbon trioxide (12C16O3) via its nu1 and nu2 vibrational modes centered around 1165 cm(-1) under matrix isolation conditions; the identification of the 12C18O3, 13C16O3, 13C18O3, 16O12C18O2, and 18O12C16O2 isotopomers of the acyclic isomer confirms the assignments.

Adsorption and dissociation of carbon trioxide on Ag(100)

“…The calculated vibrational frequencies for C 2v agree well with the reported results in Ref. 13, but DFT did not give a reasonable estimation for two e modes for D 3h . For example, the e CO stretching mode is calculated to be about 1539 cm −1 , which is 25% higher than an IR value of 1165 cm −1 [13], indicative of the importance of including low-lying excited states and their couplings with the nuclear movement in describing the CO 3 PES near the D 3h region.…”

“…Experimentally, early vibrational spectra all pointed to C 2v [11,12], while the latter was eventually identified in CO 2 ice using low-temperature matrix isolation and spectroscopy techniques [13]. Theoretically, D 3h was calculated to be only 0.1 kcal mol −1 higher in energy at the MRCI+Q(16,13)/6-311+G(3df) level [35].…”

Ground and excited states of BF3+. Coupled cluster and density functional studies

“…[1]). In contrast, CO 3 with 22 VEs was found to have a double minimum, one at D 3h , the other at C 2v symmetry, where the latter is at lower energy [2][3][4][5].…”

Photochemistry of Ions at D-region Altitudes of the Ionosphere: A Review

“…As a result, the measured electron affinity is located in a relatively wide range of values from 1.80 to 3.48 eV. This difference between the measured values of EA(CO 3 ) can be related with the existence of the CO 3 isomer (Jamieson et al 2006), the CO 3 -isomer (Relph et al 2008), and excited states of CO 3 -ions (Hiller and Vestal 1980). (1972), Hong et al (1977), Vestal and Mauclaire (1977), Tiernan and Wu (1978), Hiller and Vestal (1980), Snodgrass et al (1990) CO It follows from the study by Wang et al (2002) that two methods of data processing have been resulted in the NO 3 (H 2 O) dissociative electron detachment energy of (4.39 ± 0.49) eV and (4.62 ± 0.71) eV, and in the NO 3 (H 2 O) 2 dissociative electron detachment energy of (4.89 ± 0.51) eV and (5.22 ± 0.61) eV.…”