Panja Subhasis, Kadhane Umesh, Andersen Jens Ulrik, Holm Anne I S, Hvelplund Preben, Kirketerp Maj-Britt Suhr, Nielsen Steen Brondsted, Stochkel Kristian, Compton Robert N, Forster James S, Kilså Kristine, Nielsen Mogens Brondsted
Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark.
J Chem Phys. 2007 Sep 28;127(12):124301. doi: 10.1063/1.2771177.
We have developed an experimental technique that allows us to study the physics of short lived molecular dianions in the gas phase. It is based on the formation of monoanions via electrospray ionization, acceleration of these ions to keV energies, and subsequent electron capture in a sodium vapor cell. The dianions are stored in an electrostatic ion storage ring in which they circulate with revolution times on the order of 100 micros. This enables lifetime studies in a time regime covering five orders of magnitude, 10(-5)-1 s. We have produced dianions of 7,7,8,8-tetracyano-p-quinodimethane and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-p-quinodimethane (TCNQ-F(4)) and measured their lifetimes with respect to electron autodetachment. Our data indicate that most of the dianions were initially formed in electronically excited states in the electron transfer process. Two levels of excitation were identified by spectroscopy on the dianion of TCNQ-F(4), and the absorption spectrum was compared with spectra obtained from spectroelectrochemistry of TCNQ-F(4) in acetonitrile solution.
我们开发了一种实验技术，使我们能够研究气相中短寿命分子双阴离子的物理性质。它基于通过电喷雾电离形成单阴离子，将这些离子加速到keV能量，以及随后在钠蒸气池中进行电子捕获。双阴离子被存储在一个静电离子存储环中，它们在其中以约100微秒的旋转时间循环。这使得能够在覆盖五个数量级（10^(-5)-1秒）的时间范围内进行寿命研究。我们已经制备了7,7,8,8-四氰基对苯二醌二甲烷和2,3,5,6-四氟-7,7,8,8-四氰基对苯二醌二甲烷（TCNQ-F(4)）的双阴离子，并测量了它们相对于电子自脱离的寿命。我们的数据表明，大多数双阴离子在电子转移过程中最初是在电子激发态形成的。通过对TCNQ-F(4)双阴离子的光谱学鉴定出了两个激发水平，并将吸收光谱与在乙腈溶液中从TCNQ-F(4)的光谱电化学获得的光谱进行了比较。
