The structures of [C₄H₄]⁺˙ ions by photodissociation in an ion cyclotron resonance spectrometer

Abstract

The photodissociation of [C4H4]+' fragment ions at the ion cyclotron resonance time-scale competes with relaxation of the internal energy by infrared emission. As a result the fraction of photodissociating ions increases with light intensity. The experiments indicate that [C4H4]+' from benzene and 1,Shexadiyne consists of a mixture of 60% vinyl acetylene ions, 10% butatriene ions and 30% cyclic ions. This confirms previous conclusions from studies of the ioh-molecule reactions of [C,H,]+' with benzene. ~~ ._ -

How ergodic is the fragmentation of the pyridine cation?

“…Several ab initio calculations, carried out by different authors, are available in the literature [25][26][27]. For our part, we studied the stable isomers with the B3LYP density functional and QCISD methods using different basis sets, up to Dunning's correlation-consistent triple-dzeta basis set.…”

“…Second, this reaction requires an important reorganization of the molecular structure. An aromatic six-membered ring generates a C 4 H 4 + fragment whose most stable structure is that of the methylenecyclopropene [18][19][20][21][22][23][24][25][26][27]. Third, since the HCN fragment is characterized by a substantial dipole moment, the last step of the reaction is governed by a strongly anisotropic potential, in contradistinction to the reactions previously studied, which involved asymptotically isotropic long-range forces.…”