Carbon Dioxide in the Infra-Red Solar Spectrum

Abstract

Wave-length measurements are given for lines in thirteen vibration-rotation bands of carbon dioxide observed between 1.5μ and 2.1μ in the infra-red solar spectrum and in the laboratory. The observations were made with the McGregor spectrometer and Cashman cell of the McMath-Hulbert Observatory. Among the thirteen bands, seven originate from the ground state and two from the first excited state of ${\mathrm{C}}^{12}$ ${\mathrm{O}}_2^{16}$. The remaining four are identified with ground state transitions in the isotopic molecules ${\mathrm{C}}^{13}$ ${\mathrm{O}}_2^{16}$ and ${\mathrm{C}}^{12}$ ${\mathrm{O}}^{16}$ ${\mathrm{O}}^{18}$. The rotational constants ${\alpha }_1$, ${\alpha }_2$, and ${\alpha }_3$ have been determined from analysis of the rotational structures. The mean value found for $B_{000}$ is 0.3906 ${\mathrm{cm}}^{-1\mathrm{}}$ and for the equilibrium position $B_e=0.3920\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$.