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

通过引入用于400至500 GHz区域的四倍器，微波光谱仪的有效灵敏度得到显著提高。对倍频器特性的详细研究表明，四倍器在规定的边缘频率区域提供了显著的第五分量输出功率。这使我们能够在500和650 GHz之间的频率区域进行中等灵敏度光谱。利用高灵敏度亚毫米波光谱仪和倍增器，我们对几种瞬态分子，特别是星际分子的潜在候选者进行了研究.新星际分子的探测：利用直边山45米望远镜对TMC-1和IRC+10216观测到的几条未确认的谱线，我们将它们归属于两个新的累积烯和碳酮分子CH_2CCC和CH_2CC。另外两种自由基，SiN和HCCN，我们首先在实验室中发现了它们的光谱线，也通过使用IRAM和NRAO望远镜的观测被确定为新的星际分子。含硅分子的光谱研究：利用实验室亚毫米波光谱技术，首次在SiH_4，C_2H_2和CO混合气体放电等离子体中探测到三种新的含硅瞬态物种C_2H_2Si，CH_2Si和HSiO。它们的光谱线进行了分析，以得到精确的分子常数，从详细的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.