Premium
Crossed‐Beam Study of Co + ( 3 F 4 )+Propane: Experiment and Density Functional Theory
Author(s) -
Yi Sung Soo,
Reichert Emily L.,
Holthausen Max C.,
Koch Wolfram,
Weisshaar James C.
Publication year - 2000
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20000616)6:12<2232::aid-chem2232>3.0.co;2-m
Subject(s) - branching (polymer chemistry) , atomic physics , branching fraction , beam (structure) , propane , density functional theory , ion , chemistry , work (physics) , excitation , collision , analytical chemistry (journal) , materials science , physics , computational chemistry , thermodynamics , organic chemistry , quantum mechanics , chromatography , optics , computer security , computer science
A pulsed beam of Co + ( 3 F 4 ) crosses a pulsed beam of C 3 H 8 or C 3 D 8 gas under single collision conditions at collision energies of 0.01 eV and 0.21 eV. After a variable time delay t ext =1‐8 μs, a fast high voltage pulse extracts product ions into a field‐free flight tube for mass analysis. Consistent with earlier work, we observe prompt CoC 3 H 6 + +H 2 elimination products in 3:1 excess over CoC 2 H 4 + +CH 4 products at 0.21 eV on a 2–10 μs time scale. Long‐lived CoC 3 H 8 + complexes fragment predominantly back to Co + +C 3 H 8 reactants and to H 2 elimination products on a 6–24 μs time scale. Density functional theory (B3LYP) calculations provide energies, geometries, and harmonic vibrational frequencies at key stationary points for use in a statistical rate model of the reaction. By adjusting two key multicenter transition state (MCTS) energies downward by 4–7 kcal mol −1 , we obtain good agreement with our decay time results and with the cross section versus collision energy of Armentrout and co‐workers from 0.1‐1.0 eV. B3LYP theory succeeds in finding relative energies of the MCTSs leading to CH 4 and H 2 in the proper order to explain the different product branching ratio for Co + (which favors H 2 over CH 4 ) compared with its nearest neighbors Fe + and Ni + (which favor CH 4 over H 2 ).