Kinetic energy release of protonated methanol clusters using the low-temperature fast-atom bombardment: experiment and theory combined

Eur. J. Mass Spectrom. 10, 213–220 (2004)
DOI: 10.1255/ejms.640

Kinetic energy release of protonated methanol clusters using the low-temperature fast-atom bombardment: experiment and theory combined

Ágnes Gömöry,^a Péter Végh,^b Judit Sztáray,^a Lárszló Drahos^a and Kárroly Vékey^a*
^aChemical Research Center, Hungarian Academy of Sciences, Pusztaszeri 59-67, H- 1025 Budapest, Hungary. E-mail: vekey@chemres.hu
^bNational Institute for Research and Development of Isotopic and Molecular Technologies, R-3400 Cluj- Napolca, PO Box700, Romania

ABSTRACT:

Low-temperature fast-atom bombardment was found to be an excellent method for generating large protonated methanol clusters, (CH₃OH)_nH⁺ (n = 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).

Keywords: protonated clusters, methanol, kinetic energy release distribution, RRKM, finite heat bath theory

You can buy this paper on-line in PDF format; it costs only £11.75. Just click on the BUY on-line button. You can pay on-line through a secure server and get access immediately.