Low-temperature fast-atom bombardment was found to be an excellent method for generating large protonated methanol clusters, (CH3OH) nH+ (H = 2 to 15). Metastable dissociations of these clusters, involving elimination of one methanol molecule, were studied using mass-analyzed ion kinetic energy spectra (MIKES). From metastable peak profiles kinetic energy release (KER) distributions were obtained, even for clusters as large as (CH3OH)15H+. The results were analyzed by a simple thermal model, by the finite heat bath theory (FHBT) and by the RRKM-based MassKinetics algorithm. The KER distribution was shown to correspond to a three-dimensional translational energy distribution, implying statistical energy partitioning in the transition state. The mean KER values and transition state temperatures were found to increase with cluster size, reaching 25 meV and ∼210 K for large clusters (n = 10).
- Finite heat bath theory
- Kinetic energy release distribution
- Protonated clusters
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics