Far Infrared Spectroscopy of Molecular Ions and Short-lived Molecules using frequency tunable CW sources

我们安装了微波功率源、兆瓦级频标系统和直流放电电源，构成了一台稳频<CO_2>激光器。利用<CO_2>激光器、微波电源和<CO_2>即将国产的激光器，采用MIM二极管作为非线性元件，产生频率可调谐的连续波远红外辐射，利用微波电源、频率标准、直流放电电源、自制的放电室、InSb探测器和倍频器，研制了一台高灵敏度的毫米波和亚毫米波光谱仪。光谱仪的灵敏度高到足以研究分子离子、自由基和星际分子。所得结果总结如下。1）。首次观测到NF自由基电子激发态&lt;a^1&gt;<DELTA>（<T_e>= 12000 &lt;cm^（-1）&gt;）的微波光谱，并精确测定了其详细的分子常数。2).首次检测到了&lt;HBF^+&gt;、<H_3>&lt;S^+&gt;和<H_2>&lt;Cl^+&gt;的纯转动光谱。<H_3>&lt;S^+&gt;是含硫星际分子化学中的关键分子离子，<H_2>&lt;Cl^+&gt;也被认为存在于星际空间中。3）。用实验室微波光谱法检测到了一种新的含硫碳链分子CCS和<C_3>S。利用所获得的详细的分子常数，我们对野边山射电天文台45米射电望远镜和贝尔电话实验室7米望远镜观测到的14条未确认的星际谱线进行了归属。特别是七个最强的未识别线，包括U45379被分配到CCS自由基和S分子的三个过渡<C_3>。

We installed a microwave power source, a MW frequency standard system, and a dc discharge power supply, and constructed a frequency stabilized <CO_2> laser. The <CO_2> laser and microwave power source combined with another <CO_2> laser which will be home-made in the coming years will be used to generate frequency tunable CW far infrared radiation by using a non-linear element, MIM diode.We constructed a high-sensitivity millimeter and submillimeter spectrometer, using the microwave power source, the frequency standard, the dc discharge power supply, a home made discharge cell, an InSb detector, and a frequency multiplier. The sensitivity of the spectrometer is high enough to study molecular ions, free radicals, and interstellar molecules. The results obtained are summarized below. 1). The microwave spectrum of the NF radical in the electronically excited state <a^1> <DELTA> ( <T_e> = 12000 <cm^(-1)> ) was observed for the first time and its detailed molecular constants were precisely determined. 2).The pure rotational spectra of <HBF^+> , <H_3> <S^+> , and <H_2> <Cl^+> were detected for the first time. <H_3> <S^+> is a key molecualr ion in the chemistry of sulfur-containing interstellar molecules and <H_2> <Cl^+> is also expected to exist in interstellar space. 3). Two members of a new sulfur-containing carbon-chain molecules, CCS and <C_3> S, were detected by laboratory microwave spectroscopy. The detailed molecular constants obtained made us to assign fourteen unidentified interstellar lines observed by 45m radio telescope of Nobeyama Radio Observatory and by 7m telescope of Bell Telephone Laboratory. Particularly four of seven strongest unidentified lines including U45379 were assigned to the transitions of the CCS radical and three to the <C_3> S molecule.