Temperature Effect on Ion-Molecule Reaction of Hydrogen Transfer in γ-Irradiated 2,3-Dimehylbutane at 4 K and 77 K As Studied by Electron Spin Resonance Spectroscopy

Article abstract of DOI:10.1021/j100395a027

Drastic temperature effects on an ion-molecule reaction of H2 transfer in solid hydrocarbon systems were studied at 4 and 77 K by ESR spectroscopy.When a 2,3-dimethylbutane (DMB)-SF6 (0.55 mol percent)-i-C4H8 (0.55 mol percent) mixture is irradiated at 4 K, the DMB(+) ion in addition to the DMB radical is formed.The tetramethylethylene (TME) cation is produced by warming the irradiated DMB-SF6-i-C4H8 mixture from 4 to 77 K.The formation of the TME(+) ion observed at 77 K is interpreted in terms of the H2 transfer reaction between the DMB(+) ion and i-C4H8.This ion-molecule reaction is completely suppressed at 4 K.The suppression of the ion-molecule reaction is explained by failure of the formation of a reaction complex in the rigid matrix at 4 K.The amounts of TME(+) ions in the DMB-SF6-i-C4H8 mixture increase gradually upon storage of the irradiated mixture at 77 K.This result indicates that the transfer reaction occurs slowly at 77 K.