title: Electron-capture-induced dissociation of protoporphyrin IX ions.
abstract: Electron-capture induced dissociation of protoporphyrin cations and anions has been studied. The cations captured two electrons in two successive collisions and were converted to the corresponding even-electron anions. About one fifth of the ions lost a hydrogen atom to become radical anions but otherwise very little fragmentation was observed. The anions captured an electron to become dianions. No hydrogen loss occurred, and the only fragmentation channel observed was loss of CO2H, to give a doubly charged carbanion. Our results indicate that protoporphyrin ions are very efficient in accommodating one or even two electrons in the lowest unoccupied molecular orbital of the porphyrin macrocycle, and that electron capture induces only limited dissociation.
authors.affiliation: Centre de Recherche sur les Ions, les Matériaux et la Photonique, Caen Cedex 5, France.
authors.forename: Virgile
authors.initials: V
authors.lastname: Bernigaud
authors.forename: Kasper
authors.initials: K
authors.lastname: Drenck
authors.forename: Bernd A
authors.initials: BA
authors.lastname: Huber
authors.forename: Preben
authors.initials: P
authors.lastname: Hvelplund
authors.forename: Tristan
authors.initials: T
authors.lastname: Jabot
authors.forename: Umesh
authors.initials: U
authors.lastname: Kadhane
authors.forename: Maj-Britt Suhr
authors.initials: MB
authors.lastname: Kirketerp
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Morten Køcks
authors.initials: MK
authors.lastname: Lykkegaard
authors.forename: Bruno
authors.initials: B
authors.lastname: Manil
authors.forename: Steen Brøndsted
authors.initials: SB
authors.lastname: Nielsen
mesh_terms: D003198:Computer Simulation; D004583:Electrons; D007477:Ions; D013058:Mass Spectrometry / Q000379:methods*; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation / Q000528:radiation effects; D011524:Protoporphyrins / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D007477:Ions; D011524:Protoporphyrins; C028025:protoporphyrin IX