Submillimeter spectrum and spectroscopic constants of the arsine molecule in the ground vibrational state

The submillimeter spectrum of the arsine molecule, AsH ₃, of both the allowed R-branch transitions ( J + 1 ← J, J = 0, 1, 2, 3) and forbidden transitions of the Q branches, | K| = 4 ← 7, 5 ← 8, 6 ← 9, is investigated in the frequency range from 220 to 900 GHz. Weak absorption lines were observed by using the spectrometer RAD with sensitivity increased by a nontunable cavity cell. On the basis of the results obtained and microwave data available in the literature the rotational spectrum of the arsine molecule in the ground state is analyzed.