Spectroscopy of Multiply-Charged Transition Metal Ions Clustered with Solvent

范德比尔特大学的Lynmarie Posey在实验物理化学项目的支持下，研究了双荷电过渡金属（TM）离子与溶剂聚集的气相光谱。由于金属的第二电离电位（IP）大于配体的IP，金属离子排斥产生的正配体，所以配位双电荷的TM离子在凝聚相中很常见，而在气相中则不常见。电喷雾电离（ESI）被用来将聚集的双价离子从凝聚态转移到气相，而不使金属还原。她将结合ESI和激光光谱学来研究(a)中性溶剂的电子吸收光谱，以评估由配位或静电结合引起的电子或结构扰动；(b)最低能配体-金属电荷转移带随溶剂分子数的变化；(c) d-d跃迁。所研究的体系是第一行TM离子与不同碱度、极性、空间体积和振动结构的中性溶剂分子聚集在一起。大多数涉及过渡金属的有趣化学反应发生在凝聚态，然而提供最精确信息的分析工具通常是气相技术。显然，必须保证气相系统和冷凝相系统尽可能地相似。电喷雾电离技术可以将化学上有趣的溶液转移到气相，在气相中，高分辨率激光光谱可以提供关于二价过渡金属离子结构的极其详细的信息。

Lynmarie Posey of Vanderbilt University is supported by the Experimental Physical Chemistry Program to study the gas-phase spectroscopy of doubly-charged transition metal (TM) ions clustered with solvent. Coordinated doubly-charged TM ions are quite common in the condensed phase, but not in the gas phase, since the second ionization potential (IP) of the metal is greater than the ligand IP, and the metal ion repels the resulting positive ligand. Electrospray ionization (ESI) has been used to transfer the clustered doubly-valent ion from the condensed to the gas phase, without reduction of the metal. She will combine ESI and laser spectroscopy to study (a) the electronic absorption spectroscopy of the neutral solvent to assess the electronic or structural perturbations resulting from coordination or electrostatic binding; (b) change in the lowest energy ligand-to-metal charge transfer band as a function of the number of solvent molecules; (c) d-d transitions. Systems to be investigated are first row TM ions clustered with various neutral solvent molecules which differ in their basicity, polarity, steric bulk and vibrational structure. Most of the interesting chemistry involving transition metals occurs in the condensed phase yet the analytical tools providing the most precise information are often gas-phase techniques. It is clear then that one must ensure that the gas-phase system and condensed phase system are as similar as possible. The electrospray ionization technique will allow transfer of the chemically interesting solution phase species to the gas phase where high resolution laser spectroscopy can be brought to bear to provide extremely detailed information on the structure of the divalent transition metal ions.