Metastable electrons, high-mobility solvent anions, and charge transfer reactions in supercritical carbon dioxide.
Metastable electrons, high-mobility solvent anions, and charge transfer reactions in supercritical carbon dioxide.
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超临界二氧化碳中的亚稳态电子、高迁移率溶剂阴离子和电荷转移反应。
DOI：
10.1021/jp010325h
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发表时间：
2001
影响因子：
3.3
通讯作者：
M. Sauer
中科院分区：
文献类型：
--
作者：
I. and;M. Sauer
时间分辨直流光电导已被用来观察准自由电子和溶剂自由基阴离子在超临界CO2（ρc <$0.468 g/cm 3; Tc <$31 °C）。电子的寿命为τe 10 cm 2/（V s）。当ρ/ρc > 0.64时，乘积μeτe随溶剂密度ρ迅速增加，在ρ/ρc = 1.82时达到2.5 × 10-9 cm 2/V。溶剂阴离子的迁移率随ρ呈指数增长，比其他离子的迁移率高2 - 10倍。溶剂阴离子迁移的活化能为0.46 eV，而对于溶质离子，该能量小于20 meV。已观察到溶剂阴离子在1.0 - 3.5 eV光激发时的电子脱离。光剥离的截面随着光子能量超过1.76 eV而线性增加，并在2.82 eV处显示出肩部;光谱类似于气相中（CO2）n-团簇（n = 6−9）的光电子光谱。电子和溶剂阴离子都与非极性电子受体溶质反应，后者的气相电子能与溶剂离子反应。
Time-resolved dc photoconductivity has been used to observe quasifree electrons and solvent radical anions in supercritical CO2 (ρc ≈ 0.468 g/cm3; Tc ≈ 31 °C). The electrons have lifetime τe 10 cm2/(V s). For ρ/ρc > 0.64, the product μeτe rapidly increases with the solvent density ρ, reaching 2.5 × 10-9 cm2/V at ρ/ρc ≈ 1.82. The mobility of the solvent anions exponentially increases with ρ, being 2−10 times higher than the mobilities of other ions. The activation energy of the solvent anion migration is 0.46 eV, whereas for solute ions, this energy is less than 20 meV. Electron detachment upon 1.0−3.5 eV photoexcitation of the solvent anion has been observed. The cross section of photodetachment linearly increases with photon energy above 1.76 eV end exhibits a shoulder at 2.82 eV; the spectrum is similar to photoelectron spectra of (CO2)n- clusters (n = 6−9) in the gas phase. Both the electrons and solvent anions react with nonpolar electron acceptor solutes whose gas-phase ele...