Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

The Ionization Energy of CF3: When Does Entropy Matter in Gas-Phase Reactions?

Published

Author(s)

Karl K. Irikura

Abstract

A minor controversy has emerged recently over the value of the ionization energy of the trifluoromethyl radical, CF3. Apparently solid evidence supports both high values, IEa {nearly equal to} 9.05 eV, and low values, IEa {nearly equal to} 8.65 eV. Examining the assumptions made in the analysis of the various experimental results shows that the root of the discrepancy is the role of entropy in low-pressure, gas-phase ion chemistry. The proper treatment of entropy has itself been a more fundamental controversy for a long time. In the zero-pressure limit, conservation of energy (δE) of a molecular collision is the primary consideration, but at the high-pressure limit the free energy (δG) dictates the outcome of a reaction: what pressures qualify as
Citation
Journal of the American Chemical Society
Volume
121
Issue
No. 33

Keywords

entropy, free energy, ion chemistry, ionization energy, photoionization

Citation

Irikura, K. (1999), The Ionization Energy of CF<sub>3</sub>: When Does Entropy Matter in Gas-Phase Reactions?, Journal of the American Chemical Society (Accessed July 19, 2024)

Issues

If you have any questions about this publication or are having problems accessing it, please contact reflib@nist.gov.

Created September 1, 1999, Updated February 17, 2017