Structures and Reactivities of Negatively-Charged Clusters in Supercritical Carbon Dioxide

超临界二氧化碳中带负电团簇的结构和反应性

• 批准号: 12440160
• 负责人: NAGATA Takashi
• 金额: $ 6.14万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12440160/
• 关键词: Supercritical carbon dioxide; Mobility measurement; Negatively-charged clusters; Ab initio calculations; Photodestruction spectrum; Radical reactions; Negative-ion chemistry; 局所クラスター構造; 電子束縛状態; イオン移動度; クラスター構造

The present study aims for (i) the spectroscopic detection of (CO_2)_n^-clusters formed in a supercritical carbon dioxide (hereafter referred to as {(CO_2)_n^-}_<scf>) and (ii) the systematic study of reactivities of {(CO_2)_n^-}_<scf> in order to explore the negative-ion chemistry in supercritical carbon dioxide. The findings are summarized as follows :1.The formation of {(CO_2)_n^-}_<scf> is detected by the measurement of negative charge transport in gaseous, supercritical and liquid carbon dioxide. The mobility measurement over a wide range of CO_2 density revealed that the nascent {(CO_2)_n^-}_<scf> formed around the excess electrons are primarily in the size range of n = 5 -6, and that the negative charge transport occurs with both the hopping and the conduction band mechanisms.2.The electronic and geometrical structures of (CO_2)_n^-and [(CO_2)_n^-(H_2O)_m] are investigated by ab initio calculations at MP2/6-311++G(d, p) level for small clusters and MP2/6-31 for larger ones, demo … More nstrating the existence of almost-isoenergetic isomers having different electronic structures ("electronic isomers").3.An effort has been made to probe the nascent {(CO_2)_n^-}_<scf> formed in a supercritical pure carbon dioxide by ns time-resolved photoabsorption spectroscopy. The transient photoabsorption signal has not been detected due possibly to either small quantum yield for the {(CO_2)_n^-}_<scf> formation or small cross sections for the {(CO_2)_n^-} photoabsorption.4.The photodestruction spectra of (CO_2)_n^-are measured in the visible and uv regions by means of photofragment mass spectrometry, which provide information on the fundamental electronic properties of (CO_2)_n^-species.5.Mass spectrometric studies have revealed the reactivity of gas-phase (CO_2)_n^-and CO_2^-(H_2O)_n as carboxylation reagents for alkyl halides and conjugated alkenes. The hydration stabilizes CO_2^<・-> without deteriorating its radical reactivity. These findings open up a possibility of novel {(CO_2)_n^-}_<scf> chemistry in a supercritical carbon dioxide. Less

本研究的目的是：(1)光谱检测超临界二氧化碳中形成的(CO_2)_n^-团簇(以下简称{(CO_2)_n^-}&lt；SCF&gt；)和(Ii)系统地研究{(CO_2)_n^-}&lt；SCF&gt；以探索超临界二氧化碳中负离子化学。主要研究结果如下：1.通过对气态、超临界和液态二氧化碳中负电荷输运的测量，发现了{(CO_2)_n^-}_t；在大范围的CO_2浓度范围内的迁移率测量表明，新生的{(CO_2)_n^-_lt；SCF&gt；2.用从头算方法研究了(CO_2)_n^-和[(CO_2)_n^-(H_2O)_m]的电子结构和几何结构，对于小的团簇，用从头算方法研究了它们的电子结构和几何结构；对于大的团簇，用DEMO…方法研究了它们的电子结构和几何结构进一步证明了具有不同电子结构的近等能异构体(“电子异构体”)的存在。3.用ns时间分辨光吸收光谱研究了在超临界纯二氧化碳中形成的新生{(CO_2)_n^-}&lt；由于{(CO_2)_n^-}_lt；SCF&gt；用光碎片质谱仪测定了(CO_2)_n^-在可见光和紫外区的光破坏光谱，为(CO_2)_n^-物种的基本电子性质提供了信息。5.质谱学研究揭示了气相(CO_2)_n^-和CO_2^-(H_2O)_n作为烷基卤化物和共轭烯烃的羧化试剂的反应活性。水合作用稳定了CO_2，而不会降低其自由基活性。这些发现为超临界二氧化碳中的新型化学开辟了可能。较少

项目成果

L.Zhu et al.: "Photodissociation of gas-phase I_3^- : product branching in the visible and uv regions"Chemical Physics Letters. 350. 233-239 (2001)

L.Zhu 等人：“气相 I_3^- 的光解离：可见光和紫外区域的产物分支”《化学物理快报》。

R.A.Holroyd, K.Itoh, M.Nishikawaet: "Density inhomogeneities and electron mobility in supercritical xenon"Journal of Chemical Physics. 118. 706-710 (2003)

R.A.Holroyd、K.Itoh、M.Nishikawaet：“超临界氙中的密度不均匀性和电子迁移率”化学物理杂志。

K.Itoh et al.: "Ion mobilities in supercritical ethane, xenon, and carbon dioxide"Chemical Physics Letters. A105. 703-709 (2001)

K.Itoh 等人：“超临界乙烷、氙气和二氧化碳中的离子迁移率”化学物理快报。

L.Zhu, K.Takahashi, M.Saeki, T.Tsukuda, T.Nagata: "Photodissociation of gas-phase I_3^-: product branching in the visible and uv regions"Chemical Physics Letters. 350. 233-239 (2001)

L.Zhu、K.Takahashi、M.Saeki、T.Tsukuda、T.Nagata：“气相 I_3^- 的光解离：可见光和紫外区域的产物分支”《化学物理快报》。

T.Tsukuda, L.Zhu, M.Saeki, T.Tsukuda, T Nagata: "Photochemistry of (NO)_n^-as studied by photofragment mass spectrometry"International Journal of Mass Spectrometry. 220. 137-143 (2002)

T.Tsukuda、L.Zhu、M.Saeki、T.Tsukuda、T Nagata：“通过光碎片质谱法研究 (NO)_n^-的光化学”国际质谱杂志。