Laboratory spectra of CO2 vibrational modes in planetary ice analogs

Abstract

a b s t r a c tLaboratory spectra have shown that CO 2 is a powerful diagnostic tool for analyzing infrared data from remote observations, as it has been detected on icy moons in the outer Solar System as well as dust grain surfaces in the interstellar medium (ISM). IR absorption band profiles of CO 2 within ice mixtures containing H 2 O and CH 3 OH change with respect to temperature and mixture ratios. In this particular study, the m 3 CO 2 asymmetric stretch mode near 4.3 lm (2350 cm À1 ), overtone mode near 1.97 lm (5080 cm À1 ), and the combination bands near 2.7 lm (3700 cm À1 ), 2.8 lm (3600 cm À1 ), and 2.02 lm (4960 cm À1 ), are systematically observed in different mixtures with H 2 O and CH 3 OH in temperature ranges from 15 K to 150 K. Additionally, some high-temperature deposits (T > 50 K) of H 2 O, CH 3 OH, and CO 2 ice mixtures were performed and it was discovered that CO 2 may deposit out at higher temperatures than previously recorded. These data may then be used to interpret infrared observational data obtained from icy surfaces in the outer Solar System and beyond.

Role of a Hydroxide Layer on Cu Electrodes in Electrochemical CO2 Reduction

“…The electrodes used for the measurements were two metallic Cu films treated with 5 or 15 cycles of CV and Cu­(OH) 2 /Cu film as the untreated Cu, respectively. In the measurements, we used D 2 O as solvent instead of water to elucidate the oxidation state of Cu, because the peak corresponding to OH on Cu overlaps with the peaks of CO 2 observed near 3600 cm –1 , which were previously assigned as combination peaks of ν 1 + ν 3 or 2ν 2 + ν 3 of CO 2 . , Cu 2 O and UPD-Cu/Au films were excluded from the measurements, because they do not contribute significantly to CO 2 reduction and are not stable during long-term measurements.…”

Infrared Observations of Ganymede From the Jovian InfraRed Auroral Mapper on Juno

“…Finally, the spectral range between 4.0 and 4.5 µm (panel D) is affected by the lowest instrumental sensitivity resulting in noisier spectra. Despite these limitations, the feature D16 at 4.260 µm associated with 12 CO 2 in solid state (Quirico et al., 1999; Quirico & Schmitt, 1997; White et al., 2012) appears recurrent in all JIRAM spectra with the exception of orbit 6 where it is absent, and on orbit 19 where it is clearly shifted from 4.260 µm to 4.250 µm. A similar effect is a consequence of the complex bonding/caging of CO 2 with surrounding molecules (Cruikshank et al., 2010) as has been reproduced in the laboratory with experiments of physisorbed and implanted CO 2 in nonice materials (Hibbits & Szanyi, 2007).…”

“…4(H 2 O) shows absorptions at 2.000 and 2.100 µm (Dalton and Pitman, 2012). Apart from water ice and salts, even CO 2 could also contribute to the overall band shape since it is characterized by a narrow triplet absorption at 1.966, 2.012, and 2.070 µm (Quirico et al., 1999; Quirico & Schmitt, 1997; White et al., 2012), the longer wavelength component of which approximately corresponds with feature A2 in JIRAM spectra. Conversely, the presence of stray light in the first three bands of JIRAM makes the identification of the CO 2 triplet central feature uncertain.…”

Highly resolved infrared spectra of pure CO2ice (15–75 K)

“…A large number of laboratory spectra of solid CO 2 in different molecular environments and for different temperatures are available (Sandford & Allamandola 1990;Ehrenfreund et al 1997Ehrenfreund et al , 1999van Broekhuizen et al 2006;White et al 2009White et al , 2012. For most sources, the analysis of the CO 2 (ν 2 ) feature implies the presence of both hydrogen-rich (H 2 O:CO 2 ) and hydrogen-poor (CO:CO 2 ) CO 2 ice, as well as CH 3 OH containing CO 2 ice (Ehrenfreund et al 1998), consistent with several of the proposed formation schemes.…”