Electron spin resonance rare gas matrix studies of {sup 12}CO{sub 2}{sup {minus}}, {sup 13}CO{sub 2}{sup {minus}}, and C{sup 17}O{sup {minus}}{sub 2}: Comparison with {ital ab initio} calculations
- Chemistry Department, Furman University, Greenville, South Carolina 29613 (United States)
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)
The {sup 12}C{sup 16}O{sub 2}{sup {minus}}, {sup 13}C{sup 16}O{sub 2}{sup {minus}}, {sup 12}C{sup 17}O{sub 2}{sup {minus}}, and {sup 12}C{sup 16,17}O{sub 2}{sup {minus}} radical anions have been generated by four independent methods and isolated in neon and argon matrices for detailed ESR (electron spin resonance) investigations. Included with these experimental measurements for the various magnetic parameters of CO{sup {minus}}{sub 2} are high level {ital ab} {ital initio} calculations (MR SD-CI and others) of the {sup 13}C and {sup 17}O hyperfine {ital A} tensors. Some of the calculations included the effects of a 42-atom neon cage on the electronic structure of CO{sup {minus}}{sub 2}. Previous ESR studies of CO{sup {minus}}{sub 2} have been conducted in more perturbing environments, such as ionic crystals, where the close proximity of the counter cation can alter the anion{close_quote}s properties. A comparison of the earlier measurements in more interactive materials with these theoretical and rare gas matrix results reveals a significantly different distribution of the spin density. The neon magnetic parameters (MHz) for CO{sup {minus}}{sub 2} are {ital g}{sub {ital x}}=2.0018, {ital g}{sub {ital y}}=1.9964, {ital g}{sub {ital z}}=2.0010; for {sup 13}C, {ital A}{sub {ital x}}=320.4, {ital A}{sub {ital y}}=296.1, {ital A}{sub {ital z}}=394.5; for {sup 17}O, {ital A}{sub {ital x}}={minus}81.6, {ital A}{sub {ital y}}={minus}74.9 and {ital A}{sub {ital z}}={minus}151.8. The argon results are similar to these neon values; isotropic spectra in argon were also observed at elevated temperatures that yielded {ital g}{sub iso} and {ital A}{sub iso} parameters consistent with the low temperature (4 K) anisotropic spectra. {copyright} {ital 1996 American Institute of Physics.}
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 383748
- Journal Information:
- Journal of Chemical Physics, Vol. 105, Issue 14; Other Information: PBD: Oct 1996
- Country of Publication:
- United States
- Language:
- English
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