Disentangling the mystery of green bands of yttrium monohydride with the help of Stark spectroscopy

YH molecules were produced by laser vaporizing yttrium in the presence of He doped with H2 or NH3. Stark spectra were recorded for four bands in the 19 300–19 800 cm−1 region at electrostatic fields up to 16 kV/cm. Stark measurements proved useful in establishing rotational and Ω quantum number assignments. The permanent electric dipole moments (in Debye) were measured to be: 1.569(64), 2.325(8), 3.316(11), 2.273(6), and 1.537(8) for the X1Σ+ ground state and the 19 385, 19 746, 19 572, and 19 575 cm−1 excited states, respectively. Strong variation of the effective Ω quantum number with J was detected for the 19 572 cm−1 state.