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The Near Infrared Absorption Spectrum of Methane

1932; American Institute of Physics; Volume: 39; Issue: 1 Linguagem: Inglês

10.1103/physrev.39.83

1536-6065

John G. Moorhead,

Atmospheric Ozone and Climate

The infrared absorption spectrum of methane between 1.4\ensuremath{\mu} and 2.6\ensuremath{\mu} was obtained with an infrared spectrometer having a grating of 5000 lines to the inch. Strong bands were found in the 1.6\ensuremath{\mu} and 2.3\ensuremath{\mu} regions. The fine structure of the 2.3\ensuremath{\mu} band was resolved in the first order spectrum. The fine structure of the 1.6\ensuremath{\mu} band was resolved in the second order but not in the first order spectrum. Only at the 2.20\ensuremath{\mu} and the 1.66\ensuremath{\mu} bands could the fine structure be measured. The 2.20\ensuremath{\mu} band has spacing of 10.7 ${\mathrm{cm}}^{\ensuremath{-}1}$, giving for the value of the moment of inertia 5.17\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}40}$ c.g.s. units. The corresponding values for the 1.66\ensuremath{\mu} band are 10.4 ${\mathrm{cm}}^{\ensuremath{-}1}$ and 5.32\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}40}$ c.g.s. units. These results are quite close to the values of 9.77 ${\mathrm{cm}}^{\ensuremath{-}1}$ and 5.66\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}40}$ c.g.s. units found for the 3.31\ensuremath{\mu} band by Cooley.