Rotation-Vibration Spectra of Diatomic and Simple Polyatomic Molecules with Long Absorbing Paths VI. The Spectrum of Nitrous Oxide (N2O) below 1.2μ

Abstract

The photographic infra-red spectrum of N2O has been investigated with absorbing paths up to 4500 m atmos. Thirty-four absorption bands have been found of which twenty-three have been measured and analyzed in detail. Improved vibrational constants ωi0 and Xik have been determined which give a fair representation of all the bands. The remaining deviations which are outside the present limits of error are due to the effect of Fermi resonance between ν1 and 2ν2. Precise values of the rotational constants Bv1v2v3 have been determined for almost all vibrational levels involved in the observed bands. For the lowest vibrational level the six most accurately measured bands yield B000=0.419125 cm−1. In this case also the rotational constant D000 representing the influence of centrifugal stretching has been determined: D000=0.193×10−6 cm−1. The value of B000 is larger by 0.000091 than that derived from microwave data. From the Bv1v2v3 values the following values for the rotational constants αi have been obtained, α1=0.00170 α2=−0.00022 α3=0.00339.These values allow the determination of the rotational constant in the equilibrium position Be=0.42145 cm−1 from which the moment of inertia in the equilibrium position is found to be Ie=66.397×10−40 g cm2. The deviations of the individual Bv1v2v3 values from those obtained from the formula Bν1ν2ν3=Be−α1(ν1+12)−α2(ν2+1)−α3(ν3+12) are appreciably larger than would correspond to the errors of measurements and must be ascribed to the effect of the Fermi resonance.