High resolution study of AsHD2: Ground state and the three bending fundamental bands ν3, ν4, and ν6

For the first time the infrared spectrum of the AsHD2 molecule has been measured in the region of the bending fundamental bands ν3, ν4, and ν6 on a Fourier transform spectrometer with a resolution of 0.0024 cm−1 and analyzed. More than 5500 transitions with Jmax = 26 have been assigned and used both to obtain “ground state combination differences” and for the determination of upper state ro-vibrational energies of the triad (001000), (000100), and (000001). Rotational parameters including centrifugal distortion coefficients up to octic terms of the ground vibrational state were calculated by fitting more than 500 “ground state combination differences” with Jmax and Kamax=21. The obtained set of 24 parameters provides a rms-deviation of 0.00011 cm−1. The upper energies were fitted with 52 parameters of an effective Hamiltonian which takes into account strong resonance interactions between all vibrational states of the triad (001000), (000100), and (000001). The rms-deviation for the energy levels considered in the fit is 0.00014 cm−1.