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Does Symmetry Drive Isotopic Anomalies in Ozone Isotopomer Formation? - Response

Janssen, Christof and Marcus, R. A. (2001) Does Symmetry Drive Isotopic Anomalies in Ozone Isotopomer Formation? - Response. Science, 294 (5544). pp. 951-952. ISSN 0036-8075. doi:10.1126/science.294.5544.951a.

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Gao and Marcus presented a modified Rice, Ramsperger, Kassel, Marcus (RRKM)–based theory to explain the strange and unconventional ozone isotope effect that has puzzled scientists for years. In earlier studies, mass spectrometric and diode laser measurements of ozone isotopomers in “scrambled” oxygen mixtures pointed toward a symmetry origin for isotope fractionation. Kinetic studies, however, contradicted the dominant role of symmetry, and later experiments revealed an unconventional mass dependency, in which isotopomer formation correlates with the enthalpy of the competing isotopic exchange. Marcus and co-workers have offered a solution to this puzzle by imposing two different fractionation factors. The first was incorporated into the theory as an ad hoc factor to describe possible nonstatistical effects, which affect asymmetric and symmetric molecule formation differently. The second, which can be called zero-point energy fractionation (ZPEF), can be treated within the RRKM theory and relates to competing properties of the exit channel transition states.

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Marcus, R. A.0000-0001-6547-1469
Additional Information:© 2001 American Association for the Advancement of Science. Received 9 October 2001; accepted 16 October 2001. The studies from this laboratory were supported by the NSF.
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Issue or Number:5544
Record Number:CaltechAUTHORS:20141112-132905878
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51670
Deposited By: Tony Diaz
Deposited On:12 Nov 2014 21:35
Last Modified:10 Nov 2021 19:14

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