Transient Negative Species in Supercritical Carbon Dioxide: Electronic Spectra and Reactions of CO2 Anion Clusters†
Transient Negative Species in Supercritical Carbon Dioxide: Electronic Spectra and Reactions of CO2 Anion Clusters†
复制标题
超临界二氧化碳中的瞬态负物质：CO2 阴离子簇的电子光谱和反应†
DOI：
10.1021/jp012340s
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发表时间：
2002
影响因子：
2.9
通讯作者：
C. Jonah
中科院分区：
文献类型：
--
作者：
Kenji Takahashi;S. Sawamura;N. Dimitrijević;D. Bartels;C. Jonah
Transient absorption spectra following ionization of supercritical CO{sub 2} have been investigated using the pulse radiolysis technique. Absorption spectra measured from 400 to 800 nm suggest that at least two transient species absorb. We have previously reported that one species is (CO{sub 2}){sub 2}{sup +}. In the near UV region, we observed a transient species of which the lifetime and reactivity are different from the dimer cation. We assign this species to a dimer anion, (CO{sub 2}){sub 2}{sup -}, or an anion-molecule complex, (CO{sub 2}{sup -})(CO{sub 2}){sub x}. Comparison with the photobleaching of CO{sub 2} anion clusters in solid rare gas matrixes and their reactivity with H{sub 2} and O{sub 2} confirm the assignment. Theoretical calculations, in which solvation is taken into account, are consistent with these assignments. It is well-established that the adiabatic electron affinity of CO{sub 2} is negative, but the adiabatic electron affinity of CO{sub 2} dimer has been calculated to be 0.89 eV for D2d symmetry (CO{sub 2}){sub 2}{sup -} in the gas phase. The calculations predict that CO{sub 2}{sup -} in a model continuum solvent is stable to autodetachment.
Transient absorption spectra following ionization of supercritical CO{sub 2} have been investigated using the pulse radiolysis technique. Absorption spectra measured from 400 to 800 nm suggest that at least two transient species absorb. We have previously reported that one species is (CO{sub 2}){sub 2}{sup +}. In the near UV region, we observed a transient species of which the lifetime and reactivity are different from the dimer cation. We assign this species to a dimer anion, (CO{sub 2}){sub 2}{sup -}, or an anion-molecule complex, (CO{sub 2}{sup -})(CO{sub 2}){sub x}. Comparison with the photobleaching of CO{sub 2} anion clusters in solid rare gas matrixes and their reactivity with H{sub 2} and O{sub 2} confirm the assignment. Theoretical calculations, in which solvation is taken into account, are consistent with these assignments. It is well-established that the adiabatic electron affinity of CO{sub 2} is negative, but the adiabatic electron affinity of CO{sub 2} dimer has been calculated to be 0.89 eV for D2d symmetry (CO{sub 2}){sub 2}{sup -} in the gas phase. The calculations predict that CO{sub 2}{sup -} in a model continuum solvent is stable to autodetachment.