High-resolution ro-vibrational spectroscopy of HDO in the region of 8900-9600 cm−1

The high-resolution absorption spectrum of the HDO molecule was recorded with a Fourier-transform interferometer in the region of 8900-9600 cm−1, where the strongly interacted bands 2ν1 + ν3, 3ν1 + ν2, ν1 + 2ν2 + ν3, 2ν1 + 3ν2, 4ν2 + ν3, ν1 + 5ν2, and 7ν2 are located. About 1000 transitions were assigned to these seven bands based on the ab initio predictions [J. Chem. Phys. 106 (1997) 4618]. Altogether, 375 upper energy levels were determined, including 24 energy levels of the highly excited bending (070) state. On that basis, the necessity of the “Effective Hamiltonian” concept in the spectroscopic analysis is discussed.