{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,23]],"date-time":"2026-10-23T19:45:08Z","timestamp":1792784708199,"version":"4.5.0"},"reference-count":105,"publisher":"American Chemical Society (ACS)","issue":"40","license":[{"start":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T00:00:00Z","timestamp":1790035200000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-029"},{"start":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T00:00:00Z","timestamp":1790035200000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-037"},{"start":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T00:00:00Z","timestamp":1790035200000},"content-version":"stm-asf","delay-in-days":0,"URL":"https:\/\/doi.org\/10.15223\/policy-045"}],"funder":[{"DOI":"10.13039\/100006234","name":"Sandia National Laboratories","doi-asserted-by":"publisher","award":["NA"],"award-info":[{"award-number":["NA"]}],"id":[{"id":"10.13039\/100006234","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100009318","name":"Helmholtz Association","doi-asserted-by":"publisher","award":["NA"],"award-info":[{"award-number":["NA"]}],"id":[{"id":"10.13039\/501100009318","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/na","name":"Gas-Phase Chemical Physics program of the US Department of Energy","doi-asserted-by":"publisher","award":["NA"],"award-info":[{"award-number":["NA"]}],"id":[{"id":"10.13039\/na","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/na","name":"Swiss Light Source (SLS) located at Paul Scherrer Institute (PSI), Villigen, Switzerland","doi-asserted-by":"publisher","award":["NA"],"award-info":[{"award-number":["NA"]}],"id":[{"id":"10.13039\/na","id-type":"DOI","asserted-by":"publisher"},{"id":"https:\/\/ror.org\/03eh3y714","id-type":"ROR","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,10,8]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>The recombination of the resonance-stabilized propargyl (C3H3) radical is a key step in the formation of the first aromatic ring in combustion environments. In addition to benzene, several other C6H6 isomers can also form, as Miller and Klippenstein [J. Phys. Chem. A\u00a02003, 107 (39), 7783\u20137799] theoretically demonstrated by mapping the complex potential energy surface of the C3H3 + C3H3 system. In this work, we investigated the propargyl self-reaction experimentally by flash pyrolysis in a resistively heated silicon carbide microreactor at combustion-relevant temperatures of 1000 and 1190 K and at pressures near 10\u201320 mbar. Using photoion mass-selected threshold photoelectron spectra (ms-TPES) obtained with photoelectron photoion coincidence (PEPICO) techniques, we identified six C6H6 species: 2-ethynyl-1,3-butadiene, benzene, fulvene, cis- and trans-1,3-hexadien-5-yne, and 3,4-dimethylenecyclobutene. We further determined their branching ratios by least-squares fitting a linear combination of individual reference spectra to the experimental mass-selected photoelectron spectrum of m\/z 78. In agreement with theoretical predictions, we found 2-ethynyl-1,3-butadiene to be the most abundant C6H6 isomer, followed by benzene and fulvene.<\/jats:p>","DOI":"10.1021\/acs.jpca.6c03346","type":"journal-article","created":{"date-parts":[[2026,9,22]],"date-time":"2026-09-22T21:01:31Z","timestamp":1790110891000},"page":"7996-8010","source":"Crossref","is-referenced-by-count":0,"title":["Resolving C6H6 Isomers from\nthe Propargyl Self-Reaction at Combustion-Relevant Temperatures by\nPEPICO Spectroscopy"],"prefix":"10.1021","volume":"130","author":[{"given":"Thomas","family":"Bierkandt","sequence":"first","affiliation":[{"name":"Institute of Combustion Technology , , ,","place":["Stuttgart, Germany, 70569"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1251-4549","authenticated-orcid":true,"given":"Patrick","family":"Hemberger","sequence":"additional","affiliation":[{"name":"Paul Scherrer Institute (PSI) , , ,","place":["Villigen, Switzerland, 5232"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nina","family":"Gaiser","sequence":"additional","affiliation":[{"name":"Institute of Combustion Technology , , ,","place":["Stuttgart, Germany, 70569"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2257-2988","authenticated-orcid":true,"given":"Patrick","family":"O\u00dfwald","sequence":"additional","affiliation":[{"name":"Institute of Combustion Technology , , ,","place":["Stuttgart, Germany, 70569"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9562-8455","authenticated-orcid":true,"given":"Markus","family":"Ko\u0308hler","sequence":"additional","affiliation":[{"name":"Institute of Combustion Technology , , ,","place":["Stuttgart, Germany, 70569"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1375-0797","authenticated-orcid":true,"given":"Nils","family":"Hansen","sequence":"additional","affiliation":[{"name":"Sandia National Laboratories , , , ,","place":["Livermore, California, United States, 94551"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,9,22]]},"reference":[{"key":"2026100809064409400_cit1","doi-asserted-by":"publisher","first-page":"7783","DOI":"10.1021\/jp030375h","article-title":"The recombination of propargyl radicals and other reactions\non a C6H6 potential","volume":"107","author":"Miller","year":"2003","journal-title":"J.\nPhys. Chem. A"},{"key":"2026100809064409400_cit2","doi-asserted-by":"publisher","first-page":"2153","DOI":"10.1016\/j.combustflame.2009.07.014","article-title":"Isomer-specific combustion chemistry\nin allene and propyne flames","volume":"156","author":"Hansen","year":"2009","journal-title":"Combust. Flame"},{"key":"2026100809064409400_cit3","doi-asserted-by":"publisher","DOI":"10.1126\/sciadv.abf0360","article-title":"Gas-phase synthesis of benzene via\nthe propargyl radical self-reaction","volume":"7","author":"Zhao","year":"2021","journal-title":"Sci. Adv."},{"key":"2026100809064409400_cit4","doi-asserted-by":"publisher","first-page":"156","DOI":"10.1038\/s42004-024-01239-7","article-title":"The isomer distribution of C6H6 products from the propargyl radical gas-phase recombination investigated\nby threshold-photoelectron spectroscopy","volume":"7","author":"Hrodmarsson","year":"2024","journal-title":"Commun.\nChem."},{"key":"2026100809064409400_cit5","doi-asserted-by":"publisher","first-page":"1519","DOI":"10.1016\/S0082-0784(00)80549-4","article-title":"Exploring old and new benzene formation\npathways in\nlow-pressure premixed flames of aliphatic fuels","volume":"28","author":"Pope","year":"2000","journal-title":"Proc. Combust. Inst."},{"key":"2026100809064409400_cit6","doi-asserted-by":"publisher","first-page":"295","DOI":"10.1080\/00102209708935714","article-title":"Aromatic and polycyclic\naromatic hydrocarbon formation in a premixed propane flame","volume":"128","author":"Marinov","year":"1997","journal-title":"Combust. Sci. Technol."},{"key":"2026100809064409400_cit7","doi-asserted-by":"publisher","first-page":"295","DOI":"10.1016\/S0082-0784(89)80036-0","article-title":"Soot formation\nin combustion processes","volume":"22","author":"Glassman","year":"1989","journal-title":"Symp. Combust."},{"key":"2026100809064409400_cit8","doi-asserted-by":"publisher","first-page":"339","DOI":"10.1016\/S0010-2180(03)00113-5","article-title":"Experimental\nstudy of fuel decomposition\nand hydrocarbon growth processes for practical fuel components: heptanes","volume":"134","author":"McEnally","year":"2003","journal-title":"Combust. Flame"},{"key":"2026100809064409400_cit9","doi-asserted-by":"publisher","first-page":"247","DOI":"10.1016\/j.pecs.2005.11.003","article-title":"Studies of\naromatic hydrocarbon formation mechanisms in flames: Progress towards\nclosing the fuel gap","volume":"32","author":"McEnally","year":"2006","journal-title":"Prog. Energy Combust.\nSci."},{"key":"2026100809064409400_cit10","doi-asserted-by":"publisher","first-page":"112899","DOI":"10.1016\/j.combustflame.2023.112899","article-title":"Soot nucleation in\ndiffusion flames and the role of aromatic hydrocarbons","volume":"255","author":"Gleason","year":"2023","journal-title":"Combust. Flame"},{"key":"2026100809064409400_cit11","doi-asserted-by":"publisher","first-page":"276","DOI":"10.1021\/acs.jpca.2c06538","article-title":"Detailed Study of the\nFormation of Soot Precursors and Soot in Highly\nControlled Ethylene(\/Toluene) Counterflow Diffusion Flames","volume":"127","author":"Gleason","year":"2023","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit12","doi-asserted-by":"publisher","first-page":"41","DOI":"10.1016\/j.proci.2010.09.009","article-title":"Formation\nof nascent soot and other condensed-phase materials in flames","volume":"33","author":"Wang","year":"2011","journal-title":"Proc. Combust. Inst."},{"key":"2026100809064409400_cit13","doi-asserted-by":"publisher","first-page":"173","DOI":"10.1016\/S0010-2180(97)00068-0","article-title":"A detailed\nkinetic modeling study of aromatics formation\nin laminar premixed acetylene and ethylene flames","volume":"110","author":"Wang","year":"1997","journal-title":"Combust. Flame"},{"key":"2026100809064409400_cit14","doi-asserted-by":"publisher","first-page":"2038","DOI":"10.1039\/b110089k","article-title":"Formation and consumption\nof single-ring aromatic hydrocarbons\nand their precursors in premixed acetylene, ethylene and benzene flames","volume":"4","author":"Richter","year":"2002","journal-title":"Phys. Chem. Chem. Phys."},{"key":"2026100809064409400_cit15","doi-asserted-by":"publisher","first-page":"79","DOI":"10.1039\/b102240g","article-title":"A theoretical analysis of the reaction\nbetween propargyl and molecular oxygen","volume":"119","author":"Hahn","year":"2001","journal-title":"Faraday\nDiscuss."},{"key":"2026100809064409400_cit16","doi-asserted-by":"publisher","first-page":"7780","DOI":"10.1021\/acs.jpca.5b01127","article-title":"Kinetics\nof propargyl radical dissociation","volume":"119","author":"Klippenstein","year":"2015","journal-title":"J. Phys.\nChem. A"},{"key":"2026100809064409400_cit17","doi-asserted-by":"publisher","first-page":"88","DOI":"10.3847\/1538-4357\/acf863","article-title":"Astrochemical modeling\nof propargyl radical chemistry in TMC-1","volume":"957","author":"Byrne","year":"2023","journal-title":"Astrophys.\nJ."},{"key":"2026100809064409400_cit18","doi-asserted-by":"publisher","first-page":"A96","DOI":"10.1051\/0004-6361\/202142678","article-title":"Detection\nof the propargyl radical at \u03bb 3 mm","volume":"657","author":"Agu\u0301ndez","year":"2022","journal-title":"Astron.\nAstrophys."},{"key":"2026100809064409400_cit19","doi-asserted-by":"publisher","first-page":"565","DOI":"10.1016\/S0360-1285(00)00009-5","article-title":"Formation of polycyclic\naromatic hydrocarbons and their\ngrowth to soot\u2500a review of chemical reaction pathways","volume":"26","author":"Richter","year":"2000","journal-title":"Prog. Energy Combust. Sci."},{"key":"2026100809064409400_cit20","doi-asserted-by":"publisher","first-page":"2028","DOI":"10.1039\/b110045a","article-title":"Reaction mechanism\nof soot formation in flames","volume":"4","author":"Frenklach","year":"2002","journal-title":"Phys. Chem. Chem.\nPhys."},{"key":"2026100809064409400_cit21","doi-asserted-by":"publisher","first-page":"1477","DOI":"10.1016\/j.proci.2020.07.130","article-title":"Identification of the\nmolecular-weight growth reaction network in counterflow flames of\nthe C3H4 isomers allene and propyne","volume":"38","author":"Kukkadapu","year":"2021","journal-title":"Proc. Combust. Inst."},{"key":"2026100809064409400_cit22","doi-asserted-by":"publisher","first-page":"12112","DOI":"10.1039\/c0cp00241k","article-title":"The importance of fuel\ndissociation and propargyl + allyl association for the formation of\nbenzene in a fuel-rich 1-hexene flame","volume":"12","author":"Hansen","year":"2010","journal-title":"Phys.\nChem. Chem. Phys."},{"key":"2026100809064409400_cit23","doi-asserted-by":"publisher","first-page":"4750","DOI":"10.1021\/jp402484v","article-title":"Recombination\nof allyl radicals in the high temperature fall-off regime","volume":"117","author":"Lynch","year":"2013","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit24","doi-asserted-by":"publisher","first-page":"779","DOI":"10.1016\/j.fuel.2017.07.042","article-title":"Experimental and\nkinetic modeling study of the pyrolysis and oxidation of 1,5-hexadiene:\nThe reactivity of allylic radicals and their role in the formation\nof aromatics","volume":"208","author":"Vermeire","year":"2017","journal-title":"Fuel"},{"key":"2026100809064409400_cit25","doi-asserted-by":"publisher","first-page":"7418","DOI":"10.1021\/acs.jpca.5b00644","article-title":"Kinetics of the self reaction of\ncyclopentadienyl radicals","volume":"119","author":"Knyazev","year":"2015","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit26","doi-asserted-by":"publisher","first-page":"2291","DOI":"10.1016\/S1540-7489(02)80279-6","article-title":"The formation and oxidation of aromatics\nin cyclopentene\nand methyl-cyclopentadiene mixtures","volume":"29","author":"Lindstedt","year":"2002","journal-title":"Proc. Combust.\nInst."},{"key":"2026100809064409400_cit27","doi-asserted-by":"publisher","first-page":"9191","DOI":"10.1021\/acs.jpca.7b09873","article-title":"Kinetics\nof the CH3 + C5H5 reaction: A theoretical\nstudy","volume":"121","author":"Krasnoukhov","year":"2017","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit28","doi-asserted-by":"publisher","first-page":"4699","DOI":"10.1039\/C9CP05854K","article-title":"Role of ring-enlargement\nreactions in the formation of aromatic hydrocarbons","volume":"22","author":"Baroncelli","year":"2020","journal-title":"Phys. Chem. Chem. Phys."},{"key":"2026100809064409400_cit29","doi-asserted-by":"publisher","first-page":"3740","DOI":"10.1021\/jp0675126","article-title":"The reaction\nof n- and i-C4H5 radicals with acetylene","volume":"111","author":"Senosiain","year":"2007","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit30","doi-asserted-by":"publisher","first-page":"3670","DOI":"10.1021\/jp056769l","article-title":"Identification and chemistry of C4H3 and C4H5 isomers in fuel-rich flames","volume":"110","author":"Hansen","year":"2006","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit31","doi-asserted-by":"publisher","first-page":"623","DOI":"10.1016\/j.proci.2008.06.050","article-title":"Benzene formation\nin premixed fuel-rich 1,3-butadiene flames","volume":"32","author":"Hansen","year":"2009","journal-title":"Proc. Combust. Inst."},{"key":"2026100809064409400_cit32","doi-asserted-by":"publisher","first-page":"377","DOI":"10.1016\/j.proci.2008.06.011","article-title":"Fuel dependence\nof benzene pathways","volume":"32","author":"Zhang","year":"2009","journal-title":"Proc. Combust. Inst."},{"key":"2026100809064409400_cit33","doi-asserted-by":"publisher","first-page":"585","DOI":"10.1016\/j.proci.2010.05.056","article-title":"Fuel-structure\ndependence of benzene formation processes in premixed flames fueled\nby C6H12 isomers","volume":"33","author":"Hansen","year":"2011","journal-title":"Proc.\nCombust. Inst."},{"key":"2026100809064409400_cit34","doi-asserted-by":"publisher","first-page":"2165","DOI":"10.1021\/jp052797s","article-title":"An optimized\nsemidetailed submechanism\nof benzene formation from propargyl recombination","volume":"110","author":"Tang","year":"2006","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit35","doi-asserted-by":"publisher","first-page":"508","DOI":"10.1134\/S0010508212050024","article-title":"Exploring formation\npathways of aromatic\ncompounds in laboratory-based model flames of aliphatic fuels","volume":"48","author":"Hansen","year":"2012","journal-title":"Combust., Explos. Shock Waves"},{"key":"2026100809064409400_cit36","doi-asserted-by":"publisher","first-page":"7254","DOI":"10.1021\/jp0102973","article-title":"The recombination of propargyl radicals:\nSolving the\nmaster equation","volume":"105","author":"Miller","year":"2001","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit37","doi-asserted-by":"publisher","first-page":"21","DOI":"10.1016\/0010-2180(92)90124-8","article-title":"Kinetic and thermodynamic issues in the formation of\naromatic compounds in flames of aliphatic fuels","volume":"91","author":"Miller","year":"1992","journal-title":"Combust. Flame"},{"key":"2026100809064409400_cit38","doi-asserted-by":"publisher","first-page":"621","DOI":"10.1016\/S0082-0784(06)80076-7","article-title":"Unimolecular\nreaction mechanisms\ninvolving C3H4, C4H4,\nand C6H6 hydrocarbon species","volume":"24","author":"Melius","year":"1992","journal-title":"Symp. Combust."},{"key":"2026100809064409400_cit39","doi-asserted-by":"publisher","first-page":"19","DOI":"10.1524\/zpch.1989.161.Part_1_2.019","article-title":"Formation of C6H6 isomers by\nrecombination of propynyl in the system sodium vapour\/propynylhalide","volume":"161","author":"Alkemade","year":"1989","journal-title":"Z. Phys. Chem."},{"key":"2026100809064409400_cit40","doi-asserted-by":"publisher","first-page":"8893","DOI":"10.1021\/jp035648n","article-title":"Kinetics\nand products of the self-reaction\nof propargyl radicals","volume":"107","author":"Shafir","year":"2003","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit41","doi-asserted-by":"publisher","first-page":"6056","DOI":"10.1021\/jp050640u","article-title":"Isomeric product distributions from\nthe self-reaction of propargyl radicals","volume":"109","author":"Tang","year":"2005","journal-title":"J.\nPhys. Chem. A"},{"key":"2026100809064409400_cit42","volume-title":"A time-resolved, isomer-resolved study of\nthe propargyl self reaction using a multiplexed photoionization mass\nspectrometer","author":"Osborn","year":"2010"},{"key":"2026100809064409400_cit43","doi-asserted-by":"publisher","first-page":"9603","DOI":"10.1021\/jp0307497","article-title":"Pressure and Temperature\nEffects on Product Channels of the Propargyl\n(HC\u22eeCCH 2) Combination Reaction and the Formation\nof the \u201cFirst Ring\u201d","volume":"107","author":"Howe","year":"2003","journal-title":"J. Phys.\nChem. A"},{"key":"2026100809064409400_cit44","doi-asserted-by":"publisher","first-page":"118","DOI":"10.1002\/(SICI)1097-4601(2000)32:2&lt;118::AID-KIN8&gt;3.0.CO;2-F","article-title":"Kinetics and products\nof propargyl (C3H3) radical\nself-reactions and propargyl-methyl cross-combination reactions","volume":"32","author":"Fahr","year":"2000","journal-title":"Int. J. Chem. Kinet."},{"key":"2026100809064409400_cit45","doi-asserted-by":"publisher","first-page":"1511","DOI":"10.1016\/S0082-0784(00)80548-2","article-title":"High-temeprature\ninvestigations on\npyrolytic reactions of propargyl radicals","volume":"28","author":"Scherer","year":"2000","journal-title":"Proc.\nCombust. Inst."},{"key":"2026100809064409400_cit46","doi-asserted-by":"publisher","first-page":"85","DOI":"10.1016\/S0082-0784(06)80245-6","article-title":"A new path to benzene\nin flames","volume":"23","author":"Stein","year":"1991","journal-title":"Symp. Combust."},{"key":"2026100809064409400_cit47","doi-asserted-by":"publisher","first-page":"3403","DOI":"10.1021\/jp037311r","article-title":"Speciation of C6H6 isomers by\ngas chromatography-matrix isolation Fourier transform infrared spectroscopy\u2013mass\nspectrometry","volume":"108","author":"Anderson","year":"2004","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit48","doi-asserted-by":"publisher","first-page":"3406","DOI":"10.1021\/jp037310z","article-title":"Shock tube\nstudy of thermal rearrangement of 1,5-hexadiyne over wide temperature\nand pressure regime","volume":"108","author":"Tranter","year":"2004","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit49","doi-asserted-by":"publisher","first-page":"645","DOI":"10.1039\/D2FD00028H","article-title":"Unimolecular isomerisation of 1,5-hexadiyne\nobserved by threshold photoelectron photoion coincidence spectroscopy","volume":"238","author":"Savee","year":"2022","journal-title":"Faraday Discuss."},{"key":"2026100809064409400_cit50","doi-asserted-by":"publisher","first-page":"561","DOI":"10.1021\/acs.jpca.5c07487","article-title":"Isomer-resolved high-temperature\nchemistry of the molecular-weight growth reaction of phenyl plus propargyl","volume":"130","author":"Couch","year":"2026","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit51","doi-asserted-by":"publisher","first-page":"779","DOI":"10.1016\/j.proci.2014.05.151","article-title":"Electron ionization, photoionization and photoelectron\/photoion\ncoincidence spectroscopy in mass-spectrometric investigations of a\nlow-pressure ethylene\/oxygen flame","volume":"35","author":"Felsmann","year":"2015","journal-title":"Proc. Combust.\nInst."},{"key":"2026100809064409400_cit52","doi-asserted-by":"publisher","first-page":"1714","DOI":"10.1021\/acs.jpca.4c06549","article-title":"Identification\nof Dihydropentalenes as Products of the Molecular-Weight Growth Reaction\nof Cyclopentadienyl Plus Propargyl","volume":"129","author":"Hansen","year":"2025","journal-title":"J. Phys.\nChem. A"},{"key":"2026100809064409400_cit53","doi-asserted-by":"publisher","first-page":"597","DOI":"10.1016\/j.nima.2009.08.069","article-title":"Vacuum ultraviolet\nbeamline at the Swiss Light Source for chemical dynamics studies","volume":"610","author":"Johnson","year":"2009","journal-title":"Nucl. Instrum. Methods Phys. Res., Sect. A"},{"key":"2026100809064409400_cit54","doi-asserted-by":"publisher","first-page":"2319","DOI":"10.1021\/j100402a014","article-title":"Flash pyrolytic\nproduction of rotationally cold free radicals in a supersonic jet.\nResonant multiphoton spectrum of the 3p2A2\u201d X2A2\u201d origin\nband of methyl","volume":"90","author":"Chen","year":"1986","journal-title":"J. Phys. Chem."},{"key":"2026100809064409400_cit55","doi-asserted-by":"publisher","first-page":"4003","DOI":"10.1063\/1.1143254","article-title":"Flash pyrolysis nozzle\nfor generation\nof radicals in a supersonic jet expansion","volume":"63","author":"Kohn","year":"1992","journal-title":"Rev.\nSci. Instrum."},{"key":"2026100809064409400_cit56","doi-asserted-by":"publisher","first-page":"2196","DOI":"10.1021\/acs.jpca.2c00766","article-title":"Continuous pyrolysis microreactors:\nHot sources with little cooling? New insights utilizing cation velocity\nmap imaging and threshold photoelectron spectroscopy","volume":"126","author":"Hemberger","year":"2022","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit57","doi-asserted-by":"publisher","first-page":"15059","DOI":"10.1039\/D1CP00720C","article-title":"Gas-phase aluminium acetylacetonate\ndecomposition: revision of the current mechanism by VUV synchrotron\nradiation","volume":"23","author":"Grimm","year":"2021","journal-title":"Phys. Chem. Chem. Phys."},{"key":"2026100809064409400_cit58","doi-asserted-by":"publisher","first-page":"447","DOI":"10.1080\/0144235X.2014.967951","article-title":"The properties of a micro-reactor for the study of\nthe unimolecular decomposition of large molecules","volume":"33","author":"Guan","year":"2014","journal-title":"Int. Rev. Phys. Chem."},{"key":"2026100809064409400_cit59","doi-asserted-by":"publisher","first-page":"013944","DOI":"10.1063\/1.4984304","article-title":"CRF-PEPICO: Double\nvelocity map imaging photoelectron photoion coincidence spectroscopy\nfor reaction kinetics studies","volume":"147","author":"Szta\u0301ray","year":"2017","journal-title":"J. Chem. Phys."},{"key":"2026100809064409400_cit60","doi-asserted-by":"publisher","first-page":"9698","DOI":"10.1039\/C7CP00144D","article-title":"Advances in threshold photoelectron spectroscopy (TPES)\nand threshold photoelectron photoion coincidence (TPEPICO)","volume":"19","author":"Baer","year":"2017","journal-title":"Phys. Chem. Chem. Phys."},{"key":"2026100809064409400_cit61","doi-asserted-by":"publisher","first-page":"3763","DOI":"10.1063\/1.1593788","article-title":"Suppression\nof hot electrons in threshold photoelectron photoion\ncoincidence spectroscopy using velocity focusing optics","volume":"74","author":"Szta\u0301ray","year":"2003","journal-title":"Rev. Sci. Instrum."},{"key":"2026100809064409400_cit62","doi-asserted-by":"publisher","first-page":"084108","DOI":"10.1063\/1.2436888","article-title":"Gaussian-4 theory","volume":"126","author":"Curtiss","year":"2007","journal-title":"J. Chem. Phys."},{"key":"2026100809064409400_cit63","unstructured":"Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Petersson, G. A.; Nakatsuji, H.; et al.\n          Gaussian\n16, Revision C.02.; Gaussian, Inc.: Wallingford, CT, 2016."},{"key":"2026100809064409400_cit64","unstructured":"Mozhayskiy, V. A.; Krylov, A. I.\n          ezSpectrum; http:\/\/iopenshell.usc.edu\/downloads. (Retrieved June 2026)."},{"key":"2026100809064409400_cit65","article-title":"Gas phase ion\nenergetics data","volume-title":"NIST Chemistry WebBook,\nNIST Standard Reference Database Number 69","author":"Lias","year":"2025"},{"key":"2026100809064409400_cit66","doi-asserted-by":"publisher","first-page":"11295","DOI":"10.1021\/acs.jpclett.2c03216","article-title":"Threshold photoelectron spectrum of m-benzyne","volume":"13","author":"Gerlach","year":"2022","journal-title":"J. Phys. Chem. Lett."},{"key":"2026100809064409400_cit67","doi-asserted-by":"publisher","first-page":"394","DOI":"10.1007\/s00894-024-06191-w","article-title":"A kinetic\nand mechanistic study of\nthe self-reaction between two propargyl radicals","volume":"30","author":"Pham","year":"2024","journal-title":"J. Mol. Model."},{"key":"2026100809064409400_cit68","doi-asserted-by":"publisher","first-page":"3988","DOI":"10.1039\/C7CP08055G","article-title":"The ortho-benzyne\ncation is not planar","volume":"20","author":"Kaiser","year":"2018","journal-title":"Phys. Chem. Chem. Phys."},{"key":"2026100809064409400_cit69","doi-asserted-by":"publisher","first-page":"1223","DOI":"10.1016\/j.proci.2016.06.143","article-title":"Insights in m-xylene decomposition under fuel-rich\nconditions by imaging photoelectron photoion coincidence spectroscopy","volume":"36","author":"Bierkandt","year":"2017","journal-title":"Proc. Combust. Inst."},{"key":"2026100809064409400_cit70","doi-asserted-by":"publisher","first-page":"1474","DOI":"10.1016\/j.combustflame.2013.11.024","article-title":"Detailed kinetic\nstudy of anisole pyrolysis and oxidation to understand tar formation\nduring biomass combustion and gasification","volume":"161","author":"Nowakowska","year":"2014","journal-title":"Combust. Flame"},{"key":"2026100809064409400_cit71","doi-asserted-by":"publisher","first-page":"1579","DOI":"10.1016\/j.proci.2018.07.037","article-title":"Flame structure of laminar premixed\nanisole flames investigated by photoionization mass spectrometry and\nphotoelectron spectroscopy","volume":"37","author":"Bierkandt","year":"2019","journal-title":"Proc. Combust. Inst."},{"key":"2026100809064409400_cit72","doi-asserted-by":"publisher","first-page":"9043","DOI":"10.1021\/jp102046p","article-title":"Radical\nchemistry in the thermal decomposition of anisole and deuterated anisoles:\nAn investigation of aromatic growth","volume":"114","author":"Scheer","year":"2010","journal-title":"J. Phys.\nChem. A"},{"key":"2026100809064409400_cit73","doi-asserted-by":"publisher","first-page":"8871","DOI":"10.1021\/jp900679t","article-title":"Computed rate coefficients\nand product yields for c-C5H5 + CH3 \u2192 products","volume":"113","author":"Sharma","year":"2009","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit74","doi-asserted-by":"publisher","first-page":"9022","DOI":"10.1021\/acs.jpca.2c06670","article-title":"Threshold photoelectron spectrum\nof the phenoxy radical","volume":"126","author":"Fernholz","year":"2022","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit75","doi-asserted-by":"publisher","first-page":"1747","DOI":"10.1016\/S0016-2361(01)00059-X","article-title":"The pyrolysis of anisole (C6H5OCH3) using a hyperthermal nozzle","volume":"80","author":"Friderichsen","year":"2001","journal-title":"Fuel"},{"key":"2026100809064409400_cit76","doi-asserted-by":"publisher","first-page":"980","DOI":"10.1021\/ef402273t","article-title":"Experimental and Theoretical\nStudy on the Pyrolysis Mechanism of\nThree Coal-Based Model Compounds","volume":"28","author":"Li","year":"2014","journal-title":"Energy Fuels"},{"key":"2026100809064409400_cit77","doi-asserted-by":"publisher","first-page":"023005","DOI":"10.1103\/n1t9-l6zj","article-title":"Comparative\nStudy of Anisole and 4-Vinylanisole Pyrolysis: Insight into Char,\nTar, and Particle Formation During Lignin Pyrolysis","volume":"5","author":"Shahanand","year":"2026","journal-title":"PRX Energy"},{"key":"2026100809064409400_cit78","doi-asserted-by":"publisher","first-page":"208","DOI":"10.1021\/acs.jpclett.1c03733","article-title":"Formation\nof Benzene and Naphthalene\nthrough Cyclopentadienyl-Mediated Radical\u2013Radical Reactions","volume":"13","author":"Kaiser","year":"2022","journal-title":"J. Phys. Chem. Lett."},{"key":"2026100809064409400_cit79","doi-asserted-by":"publisher","first-page":"1429","DOI":"10.1021\/acs.jpca.2c00038","article-title":"A Conical Intersection\nInfluences the Ground State Rearrangement of Fulvene to Benzene","volume":"126","author":"Carpenter","year":"2022","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit80","doi-asserted-by":"publisher","first-page":"5467","DOI":"10.1021\/ja00852a025","article-title":"Photoelectron spectra\nof open chain C6H6 isomers","volume":"97","author":"Bischof","year":"1975","journal-title":"J. Am. Chem. Soc."},{"key":"2026100809064409400_cit81","doi-asserted-by":"publisher","DOI":"10.1002\/hlca.202400197","article-title":"Threshold photoelectron spectrum\nof 3,4-dimethylenecyclobutene","volume":"108","author":"Karaev","year":"2025","journal-title":"Helv. Chim. Acta"},{"issue":"3","key":"2026100809064409400_cit82","doi-asserted-by":"publisher","first-page":"783","DOI":"10.1002\/hlca.19710540303","article-title":"Photoelectron-spectroscopic\nevidence for the orbital sequence in fulvene and 3, 4-dimethylene-cyclobutene","volume":"54","author":"Heilbronner","year":"1971","journal-title":"Helv. Chim. Acta"},{"key":"2026100809064409400_cit83","doi-asserted-by":"publisher","first-page":"1193","DOI":"10.1002\/cber.19891220627","article-title":"Alkine\nund Cumulene, XXI. 2-Ethinyl-1,3-butadien\n\u2013 ein neues Dien fu\u0308r die Diels-Alder-Reaktion","volume":"122","author":"Bader","year":"1989","journal-title":"Chem. Ber."},{"key":"2026100809064409400_cit84","doi-asserted-by":"publisher","first-page":"249","DOI":"10.1016\/0022-2860(87)80021-2","article-title":"The conformation\nand vibrational spectra of 2-ethynyl-1,3-butadiene (3-methylene-4-pentene-yne)","volume":"158","author":"Priebe","year":"1987","journal-title":"J. Mol. Struct."},{"key":"2026100809064409400_cit85","doi-asserted-by":"publisher","first-page":"815","DOI":"10.1002\/jlac.199619960528","article-title":"Novel dienes and dienophiles, VI.\nOn the chemical behavior of 2-ethynyl-1,3-butadiene","volume":"1996","author":"Hopf","year":"1996","journal-title":"Liebigs Ann."},{"key":"2026100809064409400_cit86","doi-asserted-by":"publisher","first-page":"3340","DOI":"10.1021\/jp911132r","article-title":"Reaction\nof the C2H radical\nwith 1-butyne (C4H6): Low-temperature kinetics\nand isomer-specific product detection","volume":"114","author":"Soorkia","year":"2010","journal-title":"J. Phys.\nChem. A"},{"key":"2026100809064409400_cit87","doi-asserted-by":"publisher","first-page":"2213","DOI":"10.1002\/hlca.19770600714","article-title":"Valence ionization\nenergies of hydrocarbons","volume":"60","author":"Bieri","year":"1977","journal-title":"Helv. Chim. Acta"},{"key":"2026100809064409400_cit88","doi-asserted-by":"publisher","first-page":"2171","DOI":"10.1002\/hlca.19730560706","article-title":"Die Photoelektronen-Spektren\nmethyl-substituierter Acetylene","volume":"56","author":"Brogli","year":"1973","journal-title":"Helv. Chim.\nActa"},{"key":"2026100809064409400_cit89","doi-asserted-by":"publisher","first-page":"339","DOI":"10.1016\/0301-0104(78)85084-8","article-title":"Photoelectron\u2500photoion-coincidence\nmeasurements on 2,4-hexadiyne","volume":"29","author":"Dannacher","year":"1978","journal-title":"Chem. Phys."},{"key":"2026100809064409400_cit90","doi-asserted-by":"publisher","first-page":"754","DOI":"10.1002\/hlca.19780610223","article-title":"Tris (methylidene)-cyclopropane\n(\u201c[3]Radialene\u201d).\nPart 2. Electronic states of the molecular cation and revised UV.-absorption\nspectrum of the parent neutral","volume":"61","author":"Bally","year":"1978","journal-title":"Helv. Chim.\nActa"},{"key":"2026100809064409400_cit91","doi-asserted-by":"publisher","first-page":"11433","DOI":"10.1021\/jp0467696","article-title":"Exploration of C6H6 potential\nenergy surface: A computational effort to unravel\nthe relative stabilities and synthetic feasibility of new benzene\nisomers","volume":"108","author":"Dinadayalane","year":"2004","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit92","doi-asserted-by":"publisher","first-page":"4203","DOI":"10.1021\/acs.jpca.7b03040","article-title":"Initiation reactions in acetylene\npyrolysis","volume":"121","author":"Za\u0301dor","year":"2017","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit93","doi-asserted-by":"publisher","first-page":"2196","DOI":"10.1021\/jp111521j","article-title":"Reactions of C2H with\n1- and 2-butynes:\nAn ab initio\/RRKM study of the reaction mechanism and product branching\nratios","volume":"115","author":"Jamal","year":"2011","journal-title":"J. Phys. Chem. A"},{"key":"2026100809064409400_cit94","doi-asserted-by":"publisher","first-page":"3161","DOI":"10.1039\/D1SC00654A","article-title":"Isomer-dependent catalytic pyrolysis mechanism of the\nlignin model compounds catechol, resorcinol and hydroquinone","volume":"12","author":"Pan","year":"2021","journal-title":"Chem. Sci."},{"key":"2026100809064409400_cit95","doi-asserted-by":"publisher","first-page":"2948","DOI":"10.1021\/jz401500c","article-title":"Mass-resolved\nisomer-selective chemical analysis with imaging photoelectron photoion\ncoincidence spectroscopy","volume":"4","author":"Bodi","year":"2013","journal-title":"J. Phys. Chem. Lett."},{"key":"2026100809064409400_cit96","doi-asserted-by":"publisher","first-page":"18","DOI":"10.1016\/j.ijms.2005.08.018","article-title":"Photoionization\ncross sections for reaction intermediates in hydrocarbon combustion","volume":"247","author":"Cool","year":"2005","journal-title":"Int. J. Mass Spectrom."},{"key":"2026100809064409400_cit97","doi-asserted-by":"publisher","first-page":"107","DOI":"10.1016\/S0301-0104(97)00373-X","article-title":"A photoabsorption,\nphotodissociation and photoelectron\nspectroscopy study of C6H6 and C6D6","volume":"229","author":"Rennie","year":"1998","journal-title":"Chem. Phys."},{"key":"2026100809064409400_cit98","doi-asserted-by":"publisher","first-page":"168","DOI":"10.1016\/j.pecs.2008.10.001","article-title":"Recent contributions\nof flame-sampling molecular-beam mass spectrometry to a fundamental\nunderstanding of combustion chemistry","volume":"35","author":"Hansen","year":"2009","journal-title":"Prog.\nEnergy Combust. Sci."},{"key":"2026100809064409400_cit99","doi-asserted-by":"publisher","first-page":"261","DOI":"10.1016\/0301-0104(87)80040-X","article-title":"A study of\nthe phenyl radical by vacuum ultraviolet photoelectron spectroscopy","volume":"115","author":"Butcher","year":"1987","journal-title":"Chem. Phys."},{"key":"2026100809064409400_cit100","doi-asserted-by":"publisher","first-page":"592","DOI":"10.1039\/B513960K","article-title":"Determination\nof\nabsolute photoionization cross sections of the phenyl radical","volume":"8","author":"Sveum","year":"2006","journal-title":"Phys. Chem. Chem. Phys."},{"key":"2026100809064409400_cit101","doi-asserted-by":"publisher","first-page":"68","DOI":"10.1039\/D2FD00038E","article-title":"Predicting third-body collision efficiencies\nfor water\nand other polyatomic baths","volume":"238","author":"Jasper","year":"2022","journal-title":"Faraday Discuss."},{"key":"2026100809064409400_cit102","doi-asserted-by":"publisher","first-page":"4518","DOI":"10.1021\/cr050205w","article-title":"Modeling the kinetics of bimolecular reactions","volume":"106","author":"Ferna\u0301ndez-Ramos","year":"2006","journal-title":"Chem. Rev."},{"key":"2026100809064409400_cit103","doi-asserted-by":"publisher","first-page":"025101","DOI":"10.1063\/1.4861175","article-title":"In situ flame chemistry tracing by\nimaging photoelectron photoion coincidence spectroscopy","volume":"85","author":"O\u00dfwald","year":"2014","journal-title":"Rev. Sci. Instrum."},{"key":"2026100809064409400_cit104","doi-asserted-by":"publisher","first-page":"16751","DOI":"10.1021\/acs.jpcc.3c03120","article-title":"Photoion mass-selected\nthreshold\nphotoelectron spectroscopy to detect reactive intermediates in catalysis:\nFrom instrumentation and examples to peculiarities and a database","volume":"127","author":"Hemberger","year":"2023","journal-title":"J. Phys. Chem. C"},{"key":"2026100809064409400_cit105","doi-asserted-by":"publisher","first-page":"181","DOI":"10.1021\/acs.jpca.6b08750","article-title":"Products\nof the propargyl self-reaction at high temperatures\ninvestigated by IR\/UV ion dip spectroscopy","volume":"121","author":"Constantinidis","year":"2017","journal-title":"J. Phys. Chem. A"}],"container-title":["The Journal of Physical\nChemistry A"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/acs.jpca.6c03346","content-type":"application\/pdf","content-version":"vor","intended-application":"unspecified"},{"URL":"https:\/\/pubs.acs.org\/jpcafh\/article-pdf\/130\/40\/7996\/68609831\/acs.jpca.6c03346.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.acs.org\/jpcafh\/article-pdf\/130\/40\/7996\/68609831\/acs.jpca.6c03346.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T13:18:23Z","timestamp":1791465503000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.acs.org\/jpcafh\/article\/130\/40\/7996\/5435941\/Resolving-C6H6-Isomers-from-the-Propargyl-Self"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,22]]},"references-count":105,"journal-issue":{"issue":"40","published-online":{"date-parts":[[2026,9,22]]},"published-print":{"date-parts":[[2026,10,8]]}},"URL":"https:\/\/doi.org\/10.1021\/acs.jpca.6c03346","relation":{},"ISSN":["1089-5639","1520-5215"],"issn-type":[{"value":"1089-5639","type":"print"},{"value":"1520-5215","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,22]]}}}