Reactive cross sections for isotopic variants of the H'+H''Br abstraction reaction: A classical trajectory study

Journal Article · Fri Jan 15 04:00:00 EST 1982 · J. Chem. Phys.; (United States)

OSTI ID:5815535

Mayne, H R; Polanyi, J C

Differing dynamics for isotopically related reactions (H'+H''Br..-->..H'H''+Br, with H' = H, D and H'' = H, D in the present work) must be explicable in terms of different patterns of motion under the influence of the same forces; i.e., kinematic effects. We have identified two prominent kinematic effects in the family of reactions under study. Both effects rendered D+HBr (symbolized (D, H)) and H+DBr (H, D) the extreme mass combinations, but the effects were opposite in sign. The alignment effect increased the reactive cross section for (D, H) compared with (H, D), since the former mass combination had longer in which to align (slower approach) and aligned more rapidly (faster molecular rotation). The rebound effect, by contrast, reduced the reactive cross section for (D, H) relative to (H, D), since in the former case the light central atom tended to rebound to re-form reagents. Either the alignment or the rebound effect could be made to dominate, depending on the choice of potential-energy surface; an increased bending force constant favored the former effect, and an earlier barrier the latter.

• Research Organization: Department of Chemistry, University of Toronto, Toronto, Canada M5S 1A1
• OSTI ID: 5815535
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 76:2; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CROSS SECTIONS
DEUTERIUM
ELEMENTS
HYDROBROMIC ACID
HYDROGEN
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
INORGANIC ACIDS
ISOTOPE EFFECTS
ISOTOPES
KINETICS
LIGHT NUCLEI
NONMETALS
NUCLEI
ODD-ODD NUCLEI
REACTION KINETICS
STABLE ISOTOPES