Moderating and Reactive Collisions of Hot Hydrogen Atoms: A Study on Isotope Effects in Methyl Fluoride

Journal Article · Sat Apr 20 04:00:00 EST 1963 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja00891a008· OSTI ID:4732232

Jurgeleit, H. Clement.; Wolfgang, Richard.

Measurements on the isotope effect on the reaction of hot hydrogen atoms with protonated and deuterated methyl fluoride were made. Recoil tritium from the He³(n,p)H³ reaction was used as the source of hot hydrogen. The yield of total hot reaction products incorporating the tritium atom (with the exception of TF, which was not measured) was 18% lower in CD₃F than in CH₃F. Smaller variations were found in the relative yields of the various products. The results can be accounted for by either several types of isotope effects on the reactive collision, or, more simply, by a greater moderating power of CD₃F compared to CH₃F. The implications of the latter hypothesis were quantitatively examined using idealized models of the moderation process. It appears that in the energy range where hot combination reactions occur, moderating as well as reactive collisions effectively involve only a small portion of the mass of the molecule struck, although that portion is probably larger than would correspond to a single atom. It was concluded that the mean energies at which the various hot reactions take place are H abstraction < H displacement < F displacement < 2 atom displacement; the billiard ball mechanism of hot reaction is inapplicable; a possible secondary isotope effect on fluorine displacement has a magnitude less than experimental error; and no effect on hot reaction of the difference in bond strength between C- H and C- D was observed. Finally, if any such bond energy effect exists it is probably less than 5% per kilocalorie.

• Research Organization: Yale Univ., New Haven
• Sponsoring Organization: USDOE
• NSA Number: NSA-17-020065
• OSTI ID: 4732232
• Journal Information: Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 8 Vol. 85; ISSN 0002-7863
• Publisher: American Chemical Society (ACS)
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ATOMS
CHEMISTRY
COLLISIONS
DEUTERIUM COMPOUNDS
FLUORIDES
HELIUM 3
HYDROGEN
ISOTOPE EFFECTS
MEASURED VALUES
METHYL RADICALS
NUCLEAR REACTIONS
RECOILS
TRITIUM