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The authors complete calculations of the boundary of adsorption lines of CO and CO2 molecules under the limited volume. The cells with the transverse size from 10 to 200 nm are considered. The inaccuracy of the half-breadth of the lines appearing when the cylindrical and spherical cells are modeled with rectangular cells was estimated. When calculating the shifts and the half-breadth of the lines of CO and CO2 molecules the authors consider the model in which CO and CO2 molecules adsorbed on the walls of the pore may cease their rotational motion.

An expression for the fourth-order rotational correction terms of the effective dipole moments of nonrigid asymmetric rotors has been derived using the method of contact transformation. The treatment takes into account the large-amplitude bending motion. The correction terms have been calculated for the different bending states of the H2O molecule. A poor convergence of the rotational series for this molecule has been obtained and some different nonpolynomial forms for these series, obtained by different summation methods, have been proposed and tested.

The previously developed generating function model is applied in this paper to fitting high rotational levels of the water molecule in the domain of rotational quantum numbers where the standard power series expansion of the rotational Hamiltonian has a slow rate of convergence or even diverges. This model typically provides a considerable improvement in the standard deviation of fit with respect both to the conventional polynomial Hamiltonian and to the Pade-type Hamiltonian (with the same or fewer number of adjustable parameters). Ground state rotational levels recovered by Flaud et al.(Mol. Phys.32,499-521 (1976)) from flame spectra are fitted with accuracy near that of the experimental values: weighted standard deviation χ = 1.8 for 422 levels up to J, Ka≤ 20 and χ = 2.1 for all available levels up to J≤ 35. New ground state data reported by Toth (J. Opt. Soc.B8,2236-2255 (1991)) are fitted up to J, Ka≤ 10 with RMS = 4 × 10−5cm−1. Tests of extrapolation properties of the generating function model are discussed. In certain cases the accuracy of extrapolation was better than the accuracy of fitting with the standard rotational Hamiltonian.