The infrared matrix isolation spectra of ND₃ and NH₃ in an argon matrix in the v₂ bending region

Abstract

The spectra of NH₃ and ND₃ in an argon matrix have been obtained in the v₂ (bending fundamental) region. The v₂ region of ND₃ has been interpreted in terms of a gas-phase model, with slightly altered rotational constants. Thus for the matrix an effective value of (B'+B') = 9.85 is required compared with 10.25 cm^-1 for the gas phase. This represents a smaller fractional change than for NH₃. The inversion splitting of ND₃ in the argon matrix has been clearly resolved and a value of 2.0±0.1 cm^-1 deduced. However, there are extra lines in the spectrum of ND₃ which we cannot assign on the basis of a gas-phase model. For NH₃ some vib-rotor 'lines' have been shown to be composite, in particular Q(1₁⁺) and Q(1₁^-) are close triplets.