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Photodegradation of bromocarbons is one of the main sources of bromine atoms in the atmosphere. Here, we use high-level ab\u00a0initio methods, including spin\u2013orbit effects, to study the photodissociation of the CH2Br radical. All possible fragmentation pathways, namely CH2Br + h\u03bd \u2192 CH2 + Br, HCBr + H, and CBr + H2, have been analyzed. Potential-energy curves of the ground and several excited electronic states along the corresponding dissociating bond distance of each pathway have been calculated. Considering the actinic fluxes of solar irradiation in the troposphere and in the stratosphere in the relevant range of frequencies, it is found that the first five excited states of CH2Br can be accessed from the ground state. Analysis of the potential curves shows that the pathways producing CH2 + Br and HCBr + H can proceed through a fast direct dissociation mechanism, while the pathway leading to CBr + H2 involves much slower dissociation mechanisms like internal conversion between electronic states, predissociation, or tunneling through exit barriers. The main implications are that the two faster channels are predicted to be dominant, and the slower pathway is expected to be less relevant. The tropospheric and stratospheric solar actinic fluxes also allow for further dissociation of the HCBr and CBr fragments, generating additional Br atoms, provided that they survive possible collisions with other atmospheric reagents. Finally, we discuss the possible effect of each of the three CH2Br dissociation pathways on the depletion of atmospheric ozone.<\/jats:p>","DOI":"10.1063\/5.0187546","type":"journal-article","created":{"date-parts":[[2024,2,16]],"date-time":"2024-02-16T19:54:43Z","timestamp":1708113283000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":3,"title":["Photodissociation of the CH2Br radical: A theoretical study"],"prefix":"10.1063","volume":"160","author":[{"ORCID":"https:\/\/orcid.org\/0009-0002-3097-4589","authenticated-orcid":false,"given":"F.","family":"Charfeddine","sequence":"first","affiliation":[{"name":"Laboratoire de Spectroscopie Atomique, Moleculaire et Applications-LSAMA LR01ES09, Faculte des Sciences de Tunis, Universite de Tunis El Manar 1 , 2092 Tunis, Tunisia"},{"name":"Instituto de F\u00edsica Fundamental, Consejo Superior de Investigaciones Cient\u00edficas 2 , Serrano 123, 28006 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0471-5658","authenticated-orcid":false,"given":"A.","family":"Zanchet","sequence":"additional","affiliation":[{"name":"Instituto de F\u00edsica Fundamental, Consejo Superior de Investigaciones Cient\u00edficas 2 , Serrano 123, 28006 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4462-829X","authenticated-orcid":false,"given":"O.","family":"Yazidi","sequence":"additional","affiliation":[{"name":"Laboratoire de Spectroscopie Atomique, Moleculaire et Applications-LSAMA LR01ES09, Faculte des Sciences de Tunis, Universite de Tunis El Manar 1 , 2092 Tunis, Tunisia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9251-5460","authenticated-orcid":false,"given":"C. A.","family":"Cuevas","sequence":"additional","affiliation":[{"name":"Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Blas Cabrera, CSIC 3 , 28006 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0060-1581","authenticated-orcid":false,"given":"A.","family":"Saiz-Lopez","sequence":"additional","affiliation":[{"name":"Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Blas Cabrera, CSIC 3 , 28006 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0777-2375","authenticated-orcid":false,"given":"L.","family":"Ba\u00f1ares","sequence":"additional","affiliation":[{"name":"Departamento de Qu\u00edmica F\u00edsica, Facultad de Ciencias Qu\u00edmicas, Universidad Complutense de Madrid (Unidad Asociada I+D+i CSIC) 4 , 28040 Madrid, Spain"},{"name":"Instituto Madrile\u00f1o de Estudios Avanzados en Nanociencia (IMDEA-Nanoscience) 5 , 28049 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1214-2132","authenticated-orcid":false,"given":"A.","family":"Garc\u00eda-Vela","sequence":"additional","affiliation":[{"name":"Instituto de F\u00edsica Fundamental, Consejo Superior de Investigaciones Cient\u00edficas 2 , Serrano 123, 28006 Madrid, Spain"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"317","published-online":{"date-parts":[[2024,2,16]]},"reference":[{"volume-title":"Reactive Intermediate Chemistry","year":"2004","key":"2024021619542079600_c1"},{"key":"2024021619542079600_c2","doi-asserted-by":"publisher","first-page":"303","DOI":"10.1016\/S1387-3806(99)00178-5","article-title":"Ab initio insights into amide bond cleavage reactions of formamide with substituted methyl cations XCH2+ (X = OH, F, and Cl)","volume":"195\u2013196","year":"2000","journal-title":"Int. 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