Fluid dinitrogen tetroxide at very high pressure and high temperature: observation of the nitrite isomer
| Autor: | S. F. Agnew, D. A. Pinnick, Basil I. Swanson |
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| Rok vydání: | 1992 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry. 96:7092-7096 |
| ISSN: | 1541-5740 0022-3654 |
| DOI: | 10.1021/j100196a046 |
| Popis: | Infrared and UV-visible absorption spectra have been obtained for samples of N{sub 2}O{sub 4} contained in diamond-anvil cells at high pressures and high temperatures. Infrared spectra allow characterization of the phase and chemistry of N{sub 2}O{sub 4} as a function of temperature and pressure, while UV-visible absorption spectra allow an independent measure of {Delta}H and correlation with previous measurements. Three new peaks appear in the IR spectra at low pressures and elevated temperatures in the liquid phase, one in the NO{sub 2} stretching region, one in the NO stretching region, and the third in the NON stretching region, all of which we assign to the nitrite isomer of N{sub 2}O{sub 4}, O{sub 2}N-O-NO. The appearance of these features is reversible and allows one to measure a {Delta}H for the isomerization, both with IR and UV-visible absorption spectroscopies. The {Delta}H for isomerization at 0.4 GPa is 19.1 {plus_minus} 0.8 kJ/mol, which is compared with previous measurements for the dissociation of N{sub 2}O{sub 4} at ambient pressure. The authors find that the heretofore unreported presence of isomerization interfered with the previously measured {Delta}H for N{sub 2}O{sub 4} dissociation in solution (determined with UV-visible absorption), and correction to these previous low-pressure data bringsmore » it into better agreement with independent ESR measurements on the dissociation. 17 refs., 8 figs., 2 tabs.« less |
| Databáze: | OpenAIRE |
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