Recent spectroscopic observations by sensitive radio telescopes require accurate molecular spectral line frequencies to identify molecular species in a forest of lines detected. To measure rest frequencies of molecular spectral lines in the laboratory, an emission-type millimeter and submillimeter-wave spectrometer utilizing state-of-the-art radio-astronomical technologies is developed. The spectrometer is equipped with a 200 cm glass cylinder cell, a two-sideband (2SB) superconductor-insulator-superconductor (SIS) receiver in the 230 GHz band, and wide-band auto-correlation digital spectrometers. By using the four 2.5 GHz digital spectrometers, a total instantaneous bandwidth of the 2SB SIS receiver of 8 GHz can be covered with a frequency resolution of 88.5 kHz. Spectroscopic measurements of CH3CN and HDO are carried out in the 230 GHz band so as to examine the frequency accuracy, stability, sensitivity, as well as the intensity calibration accuracy of our system. As for the result of CH3CN, we confirm that the frequency accuracy for lines detected with sufficient signal-to-noise ratio is better than 1 kHz, when the high-resolution spectrometer having a channel resolution of 17.7 kHz is used. In addition, we demonstrate the capability of this system by spectral scan measurement of CH3OH from 216 GHz to 264 GHz. We assign 242 transitions of CH3OH, 51 transitions of 13CH3OH, and 21 unidentified emission lines for 295 detected lines. Consequently, our spectrometer demonstrates sufficient sensitivity, spectral resolution, and frequency accuracy for in-situ experimental-based rest frequency measurements of spectral lines for various molecular species.

中文翻译：

---

使用超导混频器接收器 (SUMIRE) 进行实验室亚毫米光谱仪的光谱仪

最近由敏感射电望远镜进行的光谱观测需要准确的分子谱线频率来识别检测到的谱线森林中的分子种类。为了在实验室测量分子谱线的静止频率，开发了一种利用最先进的射电天文技术的发射型毫米波和亚毫米波光谱仪。该光谱仪配备了一个 200 cm 玻璃圆柱池、一个 230 GHz 频段的双边带 (2SB) 超导体-绝缘体-超导体 (SIS) 接收器和宽带自相关数字光谱仪。通过使用四个 2.5 GHz 数字光谱仪，8 GHz 的 2SB SIS 接收器的总瞬时带宽可以覆盖 88.5 kHz 的频率分辨率。CH3CN 和 HDO 的光谱测量在 230 GHz 频段进行，以检查我们系统的频率精度、稳定性、灵敏度以及强度校准精度。对于 CH3CN 的结果，我们确认当使用具有 17.7 kHz 通道分辨率的高分辨率光谱仪时，以足够的信噪比检测到的谱线的频率精度优于 1 kHz。此外，我们通过从 216 GHz 到 264 GHz 的 CH3OH 光谱扫描测量来展示该系统的能力。我们分配了 242 个 CH3OH 跃迁、51 个 13CH3OH 跃迁和 21 个未识别的发射谱线，用于 295 条检测到的谱线。因此，我们的光谱仪表现出足够的灵敏度、光谱分辨率、