{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T11:00:02Z","timestamp":1790852402391,"version":"4.1.0"},"reference-count":30,"publisher":"AIP Publishing","issue":"13","funder":[{"name":"Russian Federal Ministry of Science and Higher Education","award":["FWGF-2026-0011"],"award-info":[{"award-number":["FWGF-2026-0011"]}]}],"content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2026,10,7]]},"abstract":"<jats:p>The photogeneration of the singlet sigma state of oxygen O2b1\u03a3g+ from van der Waals complexes of butadiene with oxygen C4H6\u2212O2 was revealed and investigated under the molecular beam conditions. The action spectrum of O2b1\u03a3g+ photogeneration, detected by resonance-enhanced multiphoton ionization (2 + 1), is measured with the two-laser pump\u2013probe approach. The spectral location of the center near 250\u00a0nm and red-side edge of the action spectrum near 290\u00a0nm coincide very well with the numbers expected for the double spin-flip process C41H6\u2212O2+h\u03bd\u21923C43H6+O2(\u03a3g+1, as they are estimated within a weak-coupling model. Velocity map imaging of the singlet sigma state of oxygen indicates formation of two ensembles (translationally \u201ccold\u201d and \u201chot\u201d) with the increase in the \u201chot\u201d component contribution with rising photon energy. The \u201ccold\u201d component with the translational temperature independent of the photon energy is provided by direct complex dissociation after \u201cvertical\u201d excitation on the repulsive wall of the van der Waals potential. The presence of the translationally \u201chot\u201d component is attributed to partial redistribution of the energy of vibrationally excited triplet butadiene to the van der Waals bond on a time scale of complex dissociation. The revealed photoinduced double spin-flip is expected to take place for any weakly bound complexes of oxygen (encounter complexes X \u2212 O2 in gas phase and contact complexes in condensed phase). The results obtained also indicate the accessibility of numerous supramolecular double spin-flip transitions in complexes X \u2212 O2, giving rise to the pair-states, involving any singlet state of oxygen and any triplet state of a complex partner.<\/jats:p>","DOI":"10.1063\/5.0354238","type":"journal-article","created":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T10:48:43Z","timestamp":1790851723000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["Photogeneration of the singlet sigma state of oxygen O2(\n                    <i>b<\/i>\n                    1\u03a3\n                    <i>g<\/i>\n                    +) via double spin\u2013flip transition in van der Waals complex of butadiene with oxygen C4H6 \u2212 O2"],"prefix":"10.1063","volume":"165","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8746-6238","authenticated-orcid":false,"given":"Vladislav M.","family":"Rogoveshko","sequence":"first","affiliation":[{"name":"Voevodsky Institute of Chemical Kinetics and Combustion , Novosibirsk,","place":["Russia"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5042-888X","authenticated-orcid":false,"given":"Alexey V.","family":"Baklanov","sequence":"additional","affiliation":[{"name":"Voevodsky Institute of Chemical Kinetics and Combustion , Novosibirsk,","place":["Russia"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"317","published-online":{"date-parts":[[2026,10,1]]},"reference":[{"key":"2026100106482262100_c1","volume-title":"Singlet Oxygen: Applications in Biosciences and Nanosciences","author":"Nonell","year":"2016"},{"key":"2026100106482262100_c2","doi-asserted-by":"publisher","first-page":"9949","DOI":"10.1021\/acs.chemrev.4c00105","article-title":"Singlet oxygen photophysics: From liquid solvents to mammalian cells","volume":"124","year":"2024","journal-title":"Chem. 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