High-Sensitivity Submillimeter-Wave Spectroscopy of Silicon-Containing Interstellar Molecules

通过在400-500 GHz范围内引入四倍频管，微波光谱仪的有效灵敏度得到了显著提高。对乘法器特性的详细研究表明，该倍增器在指定的边沿频率范围内提供了相当大的5次分量输出功率。这使我们能够在500到650 GHz的频率范围内进行中等灵敏度的光谱。我们利用高灵敏度的亚毫米波光谱仪与倍增器相结合，研究了几种暂态分子，特别是潜在的星际分子。新星际分子的探测：我们指定了几条未知的谱线，分别指向Tmc-1和Irc+10216，它们是由直山45m望远镜探测到的，它们是两个新的异丁烯和碳分子，分别是CH_2CCC和CH_2CC。通过IRAM和NRAO望远镜的观察，我们首先在实验室检测到了另外两个自由基SIN和HCCN，它们的谱线也被鉴定为新的星际分子。含硅分子光谱：利用实验室亚毫米波光谱首次在SiH_4、C_2H_2和CO混合气体的放电等离子体中探测到三种新的含硅瞬变物种：C_2H_2Si、CH_2Si和HSiO。对它们的谱线进行了分析，得到了精确的分子常数，由此得到了详细分子结构的基本信息。

The effective sensitivity of the microwave spectrometer was significantly improved by introducing a quadrupler for the 400 to 500 GHz region. A detailed study on the characteristics of the multiplier revealed that the quadrupler gives significant 5th component output power in the edge frequency regions specified. This enables us to carry out moderate-sensitivity spectroscopy in the frequency region between 500 and 650 GHz. We have studied several transient molecules, especially potential candidates for interstellar molecules by using the highsensitivity submillimeter-wave spectrometer combined with the multiplier.1. Detection of new interstellar molecules : We assigned several unidentified lines, which were dbtected toward TMC-1 and IRC+10216 by Naobeyama 45 m telescope, to two new cumulene and carbone molecules, CH_2CCC and CH_2CC. The other two free radicals, SiN and HCCN, whose spectral lines we detected first in the laboratory, were also identified as new interstellar molecules by observations using IRAM and NRAO telescopes.2. Spectroscopy of silicon-containing molecules : Three new silicon-containing transient species, C_2H_2Si, CH_2Si, and HSiO, were detected for the first time in the discharged plasma of a mixture of SiH_4, C_2H_2, and CO with laboratory submillimeter-wave spectroscopy. Their spectral lines were analyzed to give precise molecular constants, from which fundamental information for detailed molecular structures were derived.