High resolution spectroscopy of radical complexes in the visible and ultraviolet regions, and determination of their intermolecular potentials

本研究计划利用Nd-YAG泵浦可调谐染料激光系统结合脉冲放电喷嘴，利用激光诱导荧光光谱技术研究自由基配合物。特别是利用倍频染料激光器，我们能够在近紫外区观察到稀有气体- oh配合物的LIF光谱，这已经得到了广泛的研究。我们在超声速射流中通过排放稀释了ar的水来产生OH自由基。通过仔细调整喷嘴的尺寸和排放条件，在更强的OH单体线之间观察到Ar-OH光谱具有良好的信噪比。由于我们已经证实我们的系统能够观察到自由基配合物的LIF光谱，我们已经开始通过释放在稀有气体中稀释的各种母体分子来寻找新的系统。到目前为止，我们已经对C_2、C_3、CN、CCN等单体自由基进行了较强的观察，并将继续寻找含有这些短寿命自由基的配合物的光谱。伴随着这些实验研究，我们开发了一个程序系统来分析自由基配合物的大振幅运动，因为自由基通常有一个未配对的电子，它的自旋和/或轨道角动量与大振幅运动耦合，其能级远比具有闭壳分子的配合物复杂。我们能够解释在稀有气体-氢氧配合物的情况下观察到的光谱模式。特别是，我们精确地处理了大振幅运动下的超精细相互作用，并表明可以从观察到的超精细图案中推导出分子间势的信息。

The present research project intended to study radical complexes by means of a laser induced fluorescence spectroscopic technique using a Nd-YAG pumped tunable dye laser system combined with a pulsed-discharge-nozzle. Especially, by utilizing a frequency doubled dye laser we were able to observe LIF spectra of a rare gas-OH complex in the near UV region, which has been studied extensively. We have produced the OH radical in the supersonic jet by discharging water diluted in Ar.Spectra of Ar-OH were observed with a good signal to noise ratio between much stronger OH monomer lines, by carefully adjusting the nozzle dimensions and discharge conditions. Since we have confirmed that our system is capable to observe LIF spectra of a radical complex, we have started to search a new system by discharging various parent molecules diluted in rare gases. So far, we were able to observe monomer radicals C_2, C_3, CN,CCN etc. fairly strongly, and are continuing the search for spectra of complexes containing these short lived radical species.Along with these experimental studies, we have developed a program system to analyze the large amplitude motion of the radical complexs, where energy levels are far more complicated than those of complexes with closed shell molecules, since the radicals usually have an unpaired electron and its spin and/or orbital angular momenta couple with the large amplitude motion. We were able to explain the observed spectral patterns in the case of the rare gas-OH complexes. Especially, we have accurately treated the hyperfine interaction under the large amplitude motion, and have shown that it is possible to derive information for the intermoleclular potential from the observed hyperfine patterns.