High-sensitivity/high-resolution submillimeter-wave to far-infrared spectroscopy

A high-sensitivity submillimeter-wave spectrometer has been developed and used to study transient molecules including free radicals, molecular ions, and unstable molecules, which are potential candidates for probing interstellar phenomena. The spectrometer can be operated up to a frequency region of 620 GHz, which is covered by a combination of Klystrons and multipliers. The sensitivity of the spectrometer is estimated to be γmax=7.5x10-10/cm corresponding to the minimum detectable number of molecules, 107/cm3. This high sensitivity enabled us to identify more than 10 new interstellar molecules in collaboration with astronomers