A few years ago, the charge-transfer reaction CO2+ + O ⟶ O+ + CO2 was investigated experimentally for the first time since the study by Fehsenfeld et al., (1970). This new investigation was conducted by Tenewitz et al., (2018). The rate coefficient k < 6 × 10−13 cm3 s−1 , concluded by Tenewitz et al. (2018), differed substantially from the value of 9.6 × 10−11 cm3 s−1 reported by Fehsenfeld et al., (1970). Fox et al., (2021) showed that the old rate constants for the two channels of the CO2+ + O interaction work much better than the new ones in reproducing chemical features of the Martian ionosphere. Here, we combine MAVEN/NGIMS and TIMED/SEE data to conduct model-observation comparisons of O+ concentrations in the dayside Martian ionosphere. We consider each orbit of the MAVEN Deep Dip 2 (DD2) campaign between 17-22 April 2015. In the model, we balance the production rate of O+ through the aforementioned charge transfer reaction and the photoionisation of O and CO2 , with the loss rate through the reaction O+ + CO2 ⟶ O2+ + CO. We find a better level of agreement between the modelled and the observed O+ concentrations— (i) towards closest approach altitudes (∼ 130 km), and (ii) when using the old rate constant instead of the new one for the charge transfer reaction CO2+ + O ⟶ O+ + CO2 .
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-515408 |
| Date | January 2023 |
| Creators | Nagar, Chinmaya |
| Publisher | Uppsala universitet, Institutionen för fysik och astronomi |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | FYSAST ; FYSPROJ1323 |
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