{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,7,30]],"date-time":"2025-07-30T11:24:48Z","timestamp":1753874688478,"version":"3.41.2"},"reference-count":51,"publisher":"AIP Publishing","issue":"24","license":[{"start":{"date-parts":[[2024,6,24]],"date-time":"2024-06-24T00:00:00Z","timestamp":1719187200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"},{"start":{"date-parts":[[2024,6,24]],"date-time":"2024-06-24T00:00:00Z","timestamp":1719187200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000266","name":"Engineering and Physical Sciences Research Council","doi-asserted-by":"publisher","award":["EP\/P021123\/1"],"award-info":[{"award-number":["EP\/P021123\/1"]}],"id":[{"id":"10.13039\/501100000266","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000006","name":"Office of Naval Research","doi-asserted-by":"publisher","award":["N000141712220"],"award-info":[{"award-number":["N000141712220"]}],"id":[{"id":"10.13039\/100000006","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["pubs.aip.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[2024,6,28]]},"abstract":"<jats:p>We investigate roaming in the photodissociation of acetaldehyde (CH3CHO), providing insights into the contrasting roaming dynamics observed for this molecule compared to formaldehyde. We carry out trajectory studies for full-dimensional acetaldehyde, supplemented with an analysis of a two-degree-of-freedom restricted model and obtain evidence for two distinct roaming pathways. Trajectories exhibit roaming at both shorter (9\u201311.5 au) and larger (14.5\u201322.9 au) maximum CH3\u2013HCO separations, characterized by differing amounts of HCO rotation. No roaming trajectories were found in the intervening gap region. The roaming dynamics near 14.5\u201322.9 au are well-reproduced by the restricted model and involve passage through a centrifugal barrier, analogous to formaldehyde roaming. However, the shorter-range 9\u201311.5 au roaming appears unique to acetaldehyde and is likely facilitated by repulsive interactions absent in the simplified models. Phase space analysis reveals that this additional roaming pathway is inaccessible in the reduced dimensionality system. The findings suggest that acetaldehyde\u2019s increased propensity for roaming compared to formaldehyde may arise from the presence of multiple distinct roaming mechanisms rather than solely the higher roaming fragment mass.<\/jats:p>","DOI":"10.1063\/5.0212443","type":"journal-article","created":{"date-parts":[[2024,6,24]],"date-time":"2024-06-24T12:23:57Z","timestamp":1719231837000},"update-policy":"https:\/\/doi.org\/10.1063\/aip-crossmark-policy-page","source":"Crossref","is-referenced-by-count":0,"title":["Roaming in acetaldehyde"],"prefix":"10.1063","volume":"160","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6052-7531","authenticated-orcid":false,"given":"Vladim\u00edr","family":"Kraj\u0148\u00e1k","sequence":"first","affiliation":[{"name":"School of Mathematics, University of Bristol 1 , Fry Building, Woodland Road, Bristol BS8 1UG, United Kingdom"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0780-0911","authenticated-orcid":false,"given":"Stephen","family":"Wiggins","sequence":"additional","affiliation":[{"name":"School of Mathematics, University of Bristol 1 , Fry Building, Woodland Road, Bristol BS8 1UG, United Kingdom"},{"name":"Department of Mathematics, United States Naval Academy 2 , Chauvenet Hall, 572C Holloway Road, Annapolis, Maryland 21402-5002, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"317","published-online":{"date-parts":[[2024,6,24]]},"reference":[{"key":"2024062411434428500_c1","doi-asserted-by":"publisher","first-page":"1664","DOI":"10.1063\/1.465335","article-title":"Evidence for a second molecular channel in the fragmentation of formaldehyde","volume":"99","year":"1993","journal-title":"J.\u00a0Chem. Phys."},{"key":"2024062411434428500_c2","doi-asserted-by":"publisher","first-page":"1158","DOI":"10.1126\/science.1104386","article-title":"The roaming atom: Straying from the reaction path in formaldehyde decomposition","volume":"306","year":"2004","journal-title":"Science"},{"key":"2024062411434428500_c3","doi-asserted-by":"publisher","first-page":"044303","DOI":"10.1063\/1.2202241","article-title":"The roaming atom pathway in formaldehyde decomposition","volume":"125","year":"2006","journal-title":"J.\u00a0Chem. Phys."},{"key":"2024062411434428500_c4","doi-asserted-by":"publisher","first-page":"044314","DOI":"10.1063\/1.2429660","article-title":"Energy dependence of the roaming atom pathway in formaldehyde decomposition","volume":"126","year":"2007","journal-title":"J.\u00a0Chem. Phys."},{"key":"2024062411434428500_c5","doi-asserted-by":"publisher","first-page":"288","DOI":"10.1016\/j.chemphys.2007.11.007","article-title":"Further aspects of the roaming mechanism in formaldehyde dissociation","volume":"347","year":"2008","journal-title":"Chem. Phys."},{"key":"2024062411434428500_c6","doi-asserted-by":"publisher","first-page":"834","DOI":"10.1021\/jz2002138","article-title":"Are roaming and conventional saddle points for H2CO and CH3CHO dissociation to molecular products isolated from each other?","volume":"2","year":"2011","journal-title":"J.\u00a0Phys. Chem. Lett."},{"key":"2024062411434428500_c7","doi-asserted-by":"publisher","first-page":"5103","DOI":"10.1021\/acs.jpca.6b00488","article-title":"Roaming under the microscope: Trajectory study of formaldehyde dissociation","volume":"120","year":"2016","journal-title":"J.\u00a0Phys. Chem. A"},{"key":"2024062411434428500_c8","doi-asserted-by":"publisher","first-page":"873","DOI":"10.1021\/ar8000734","article-title":"Roaming atoms and radicals: A new mechanism in molecular dissociation","volume":"41","year":"2008","journal-title":"Acc. Chem. Res."},{"key":"2024062411434428500_c9","doi-asserted-by":"publisher","first-page":"33","DOI":"10.1063\/pt.3.1330","article-title":"Roaming reactions: The third way","volume":"64","year":"2011","journal-title":"Phys. Today"},{"key":"2024062411434428500_c10","doi-asserted-by":"publisher","first-page":"531","DOI":"10.1146\/annurev-physchem-032210-103518","article-title":"Roaming radicals","volume":"62","year":"2011","journal-title":"Annu. Rev. Phys. Chem."},{"key":"2024062411434428500_c11","doi-asserted-by":"publisher","first-page":"2516","DOI":"10.1080\/00268976.2014.897395","article-title":"Roaming","volume":"112","year":"2014","journal-title":"Mol. Phys."},{"key":"2024062411434428500_c12","doi-asserted-by":"publisher","first-page":"7615","DOI":"10.1039\/c7cs00578d","article-title":"Theories and simulations of roaming","volume":"46","year":"2017","journal-title":"Chem. Soc. Rev."},{"key":"2024062411434428500_c13","doi-asserted-by":"publisher","first-page":"499","DOI":"10.1146\/annurev-physchem-052516-050613","article-title":"Roaming: A phase space perspective","volume":"68","year":"2017","journal-title":"Annu. Rev. Phys. Chem."},{"key":"2024062411434428500_c14","doi-asserted-by":"publisher","first-page":"77","DOI":"10.1146\/annurev-physchem-050317-020929","article-title":"Roaming reactions and dynamics in the van der Waals region","volume":"71","year":"2020","journal-title":"Annu. Rev. Phys. Chem."},{"key":"2024062411434428500_c15","doi-asserted-by":"publisher","first-page":"282","DOI":"10.1016\/j.cplett.2013.12.051","article-title":"Multiple transition states and roaming in ion\u2013molecule reactions: A phase space perspective","volume":"592","year":"2014","journal-title":"Chem. Phys. Lett."},{"key":"2024062411434428500_c16","doi-asserted-by":"publisher","first-page":"16079","DOI":"10.1073\/pnas.0604441103","article-title":"Photodissociation of acetaldehyde as a second example of the roaming mechanism","volume":"103","year":"2006","journal-title":"Proc. Natl. Acad. Sci. U. S. A."},{"key":"2024062411434428500_c17","doi-asserted-by":"publisher","first-page":"8282","DOI":"10.1021\/jp074646q","article-title":"Quasiclassical trajectory calculations of acetaldehyde dissociation on a global potential energy surface indicate significant non-transition state dynamics","volume":"111","year":"2007","journal-title":"J.\u00a0Phys. Chem. A"},{"key":"2024062411434428500_c18","doi-asserted-by":"publisher","first-page":"9344","DOI":"10.1021\/jp802331t","article-title":"\u2018Roaming\u2019 dynamics in CH3CHO photodissociation revealed on a global potential energy surface","volume":"112","year":"2008","journal-title":"J.\u00a0Phys. Chem. A"},{"key":"2024062411434428500_c19","doi-asserted-by":"publisher","first-page":"12719","DOI":"10.1073\/pnas.0802769105","article-title":"Roaming is the dominant mechanism for molecular products in acetaldehyde photodissociation","volume":"105","year":"2008","journal-title":"Proc. Natl. Acad. Sci. U. S. A."},{"key":"2024062411434428500_c20","doi-asserted-by":"publisher","first-page":"4633","DOI":"10.1039\/c4sc02266a","article-title":"Two roaming pathways in the photolysis of CH3CHO between 328 and 308 nm","volume":"5","year":"2014","journal-title":"Chem. Sci."},{"key":"2024062411434428500_c21","doi-asserted-by":"publisher","first-page":"041101","DOI":"10.1063\/1.4906457","article-title":"Communication: Photodissociation of CH3CHO at 308\u00a0nm: Observation of H-roaming, CH3-roaming, and transition state pathways together along the ground state surface","volume":"142","year":"2015","journal-title":"J.\u00a0Chem. Phys."},{"key":"2024062411434428500_c22","doi-asserted-by":"publisher","first-page":"6067","DOI":"10.1039\/c2cp22231k","article-title":"Imaging the molecular channel in acetaldehyde photodissociation: Roaming and transition state mechanisms","volume":"14","year":"2012","journal-title":"Phys. Chem. Chem. Phys."},{"key":"2024062411434428500_c23","doi-asserted-by":"publisher","first-page":"6123","DOI":"10.1039\/b708310f","article-title":"Slice imaging of the photodissociation of acetaldehyde at 248\u00a0nm. Evidence of a roaming mechanism","volume":"9","year":"2007","journal-title":"Phys. Chem. Chem. Phys."},{"key":"2024062411434428500_c24","doi-asserted-by":"publisher","first-page":"765","DOI":"10.1021\/jp906919w","article-title":"Roaming radical kinetics in the decomposition of acetaldehyde","volume":"114","year":"2010","journal-title":"J.\u00a0Phys. Chem. A"},{"key":"2024062411434428500_c25","doi-asserted-by":"publisher","first-page":"14370","DOI":"10.1021\/jp208347j","article-title":"Statistical theory for the kinetics and dynamics of roaming reactions","volume":"115","year":"2011","journal-title":"J.\u00a0Phys. Chem. A"},{"key":"2024062411434428500_c26","doi-asserted-by":"publisher","first-page":"094109","DOI":"10.1063\/1.5044532","article-title":"Influence of mass and potential energy surface geometry on roaming in Chesnavich\u2019s CH4+ model","volume":"149","year":"2018","journal-title":"J.\u00a0Chem. Phys."},{"key":"2024062411434428500_c27","doi-asserted-by":"publisher","first-page":"2615","DOI":"10.1063\/1.450331","article-title":"Multiple transition states in unimolecular reactions","volume":"84","year":"1986","journal-title":"J.\u00a0Chem. Phys."},{"key":"2024062411434428500_c28","doi-asserted-by":"publisher","first-page":"134112","DOI":"10.1063\/1.4870060","article-title":"Roaming dynamics in ion-molecule reactions: Phase space reaction pathways and geometrical interpretation","volume":"140","year":"2014","journal-title":"J.\u00a0Chem. Phys."},{"key":"2024062411434428500_c29","doi-asserted-by":"publisher","first-page":"2341","DOI":"10.1007\/s10910-018-0895-4","article-title":"The phase space geometry underlying roaming reaction dynamics","volume":"56","year":"2018","journal-title":"J.\u00a0Math. Chem."},{"key":"2024062411434428500_c30","doi-asserted-by":"publisher","first-page":"6423","DOI":"10.1039\/D0SC00063A","article-title":"Real-time tracking of the entangled pathways in the multichannel photodissociation of acetaldehyde","volume":"11","year":"2020","journal-title":"Chem. Sci."},{"key":"2024062411434428500_c31","doi-asserted-by":"publisher","first-page":"4123","DOI":"10.1021\/acs.jpclett.5b01930","article-title":"Phase space structures explain hydrogen atom roaming in formaldehyde decomposition","volume":"6","year":"2015","journal-title":"J.\u00a0Phys. Chem. Lett."},{"key":"2024062411434428500_c32","doi-asserted-by":"publisher","first-page":"18628","DOI":"10.1039\/c7cp02952g","article-title":"Photodissociation of CH3CHO at 248\u00a0nm: Identification of the channels of roaming, triple fragmentation and the transition state","volume":"19","year":"2017","journal-title":"Phys. Chem. Chem. Phys."},{"key":"2024062411434428500_c33","doi-asserted-by":"publisher","first-page":"615","DOI":"10.1134\/s1560354719060030","article-title":"Roaming at constant kinetic energy: Chesnavich\u2019s model and the Hamiltonian isokinetic thermostat","volume":"24","year":"2019","journal-title":"Regular Chaotic Dyn."},{"key":"2024062411434428500_c34","doi-asserted-by":"publisher","first-page":"2050076","DOI":"10.1142\/s0218127420500765","article-title":"Using Lagrangian descriptors to uncover invariant structures in Chesnavich\u2019s isokinetic model with application to roaming","volume":"30","year":"2020","journal-title":"Int. J. Bifurcation Chaos"},{"key":"2024062411434428500_c35","doi-asserted-by":"publisher","first-page":"5478","DOI":"10.1103\/physrevlett.86.5478","article-title":"Impenetrable barriers in phase-space","volume":"86","year":"2001","journal-title":"Phys. Rev. Lett."},{"key":"2024062411434428500_c36","doi-asserted-by":"publisher","first-page":"957","DOI":"10.1088\/0951-7715\/15\/4\/301","article-title":"The geometry of reaction dynamics","volume":"15","year":"2002","journal-title":"Nonlinearity"},{"key":"2024062411434428500_c37","doi-asserted-by":"publisher","first-page":"1072","DOI":"10.1126\/science.abc2960","article-title":"Capturing roaming molecular fragments in real time","volume":"370","year":"2020","journal-title":"Science"},{"key":"2024062411434428500_c38","doi-asserted-by":"publisher","first-page":"1950025","DOI":"10.1142\/s0218127419500251","article-title":"The Chesnavich model for ion-molecule reactions: A rigid body coupled to a particle","volume":"29","year":"2019","journal-title":"Int. J. Bifurcation Chaos"},{"key":"2024062411434428500_c39","doi-asserted-by":"publisher","first-page":"235702","DOI":"10.1088\/1751-8121\/ab8b75","article-title":"Revealing roaming on the double morse potential energy surface with Lagrangian descriptors","volume":"53","year":"2020","journal-title":"J.\u00a0Phys. A: Math. Theor."},{"key":"2024062411434428500_c40","doi-asserted-by":"publisher","first-page":"1218","DOI":"10.1063\/1.436658","article-title":"Transition states, trapped trajectories, and classical bound states embedded in the continuum","volume":"69","year":"1978","journal-title":"J.\u00a0Chem. Phys."},{"key":"2024062411434428500_c41","doi-asserted-by":"publisher","first-page":"2062","DOI":"10.1063\/1.438575","article-title":"Classical transition state theory is exact if the transition state is unique","volume":"71","year":"1979","journal-title":"J.\u00a0Chem. Phys."},{"key":"2024062411434428500_c42","doi-asserted-by":"publisher","first-page":"L435","DOI":"10.1088\/0305-4470\/37\/35\/l02","article-title":"Direct construction of a dividing surface of minimal flux for multi-degree-of-freedom systems that cannot be recrossed","volume":"37","year":"2004","journal-title":"J.\u00a0Phys. A: Math. Gen."},{"key":"2024062411434428500_c43","doi-asserted-by":"publisher","first-page":"239","DOI":"10.1007\/BF00375090","article-title":"Transport in two-dimensional maps","volume":"109","year":"1990","journal-title":"Arch. Ration. Mech. Anal."},{"key":"2024062411434428500_c44","doi-asserted-by":"publisher","first-page":"L435","DOI":"10.1088\/0305-4470\/37\/35\/L02","article-title":"Direct construction of a dividing surface of minimal flux for multi-degree-of-freedom systems that cannot be recrossed","volume":"37","year":"2004","journal-title":"J.\u00a0Phys. A: Math. Gen."},{"key":"2024062411434428500_c45","doi-asserted-by":"publisher","first-page":"292","DOI":"10.1007\/s10910-019-01083-4","article-title":"Phase space structures causing the reaction rate decrease in the collinear hydrogen exchange reaction","volume":"58","year":"2020","journal-title":"J.\u00a0Math. Chemistry"},{"key":"2024062411434428500_c46","doi-asserted-by":"publisher","first-page":"193","DOI":"10.1512\/iumj.1972.21.21017","article-title":"Persistence and smoothness of invariant manifolds for flows","volume":"21","year":"1971","journal-title":"Indiana Univ. Math. J"},{"volume-title":"Normally Hyperbolic Invariant Manifolds in Dynamical Systems","year":"1994","key":"2024062411434428500_c47"},{"key":"2024062411434428500_c48","doi-asserted-by":"publisher","first-page":"013111","DOI":"10.1063\/1.3056050","article-title":"Distinguished trajectories in time dependent vector fields","volume":"19","year":"2009","journal-title":"Chaos"},{"key":"2024062411434428500_c49","doi-asserted-by":"publisher","first-page":"032204","DOI":"10.1103\/physreve.98.032204","article-title":"Binary contraction method for the construction of time-dependent dividing surfaces in driven chemical reactions","volume":"98","year":"2018","journal-title":"Phys. Rev. E"},{"key":"2024062411434428500_c50","doi-asserted-by":"publisher","first-page":"054107","DOI":"10.1063\/1.4940798","article-title":"Phase space barriers and dividing surfaces in the absence of critical points of the potential energy: Application to roaming in ozone","volume":"144","year":"2016","journal-title":"J.\u00a0Chem. Phys."},{"key":"2024062411434428500_c51","doi-asserted-by":"publisher","first-page":"17890","DOI":"10.1039\/d0cp01362e","article-title":"Detecting reactive islands in a system-bath model of isomerization","volume":"22","year":"2020","journal-title":"Phys. Chem. Chem. Phys."}],"container-title":["The Journal of Chemical Physics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.aip.org\/aip\/jcp\/article-pdf\/doi\/10.1063\/5.0212443\/20007193\/244104_1_5.0212443.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/pubs.aip.org\/aip\/jcp\/article-pdf\/doi\/10.1063\/5.0212443\/20007193\/244104_1_5.0212443.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.aip.org\/aip\/jcp\/article-pdf\/doi\/10.1063\/5.0212443\/20007193\/244104_1_5.0212443.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,5,27]],"date-time":"2025-05-27T20:20:51Z","timestamp":1748377251000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.aip.org\/jcp\/article\/160\/24\/244104\/3299191\/Roaming-in-acetaldehyde"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,6,24]]},"references-count":51,"journal-issue":{"issue":"24","published-print":{"date-parts":[[2024,6,28]]}},"URL":"https:\/\/doi.org\/10.1063\/5.0212443","relation":{},"ISSN":["0021-9606","1089-7690"],"issn-type":[{"type":"print","value":"0021-9606"},{"type":"electronic","value":"1089-7690"}],"subject":[],"published-other":{"date-parts":[[2024,6,28]]},"published":{"date-parts":[[2024,6,24]]},"article-number":"244104"}}