The Fine Structures ofHαandDαUnder Varying Discharge Conditions

The fine structures of $\mathrm{H}\alpha$ and $\mathrm{D}\alpha$ have been observed under varying conditions of excitation in the discharge tube with pure hydrogen and pure deuterium maintained in each case at near liquid-air temperature, and with the aid of a Zeiss triple-prism spectrograph and a pair of Hilger quartz interferometer plates. The interference patterns obtained upon the photographic plates were analyzed with a Moll microphotometer. The microphotometer curves were reduced to intensity curves and to linear dispersion curves in the usual manner. From the final reduced curves analyses were made of the intensities and positions of the fine structure components. Within the limits of error of the observations the positions of the fine structure components were found to be invariant with changing discharge conditions. The average interval between the two main components of the complex was found to be 0.319 ${\mathrm{cm}}^{-1\mathrm{}}$ for $\mathrm{H}\alpha$ and 0.321 ${\mathrm{cm}}^{-1\mathrm{}}$ for $\mathrm{D}\alpha$. The second and third most intense components were optically resolved from each other in $\mathrm{D}\alpha$ but not in $\mathrm{H}\alpha$. The average interval between these components was found to be 0.130 ${\mathrm{cm}}^{-1\mathrm{}}$. According to theory these intervals are respectively 0.328 ${\mathrm{cm}}^{-1\mathrm{}}$ and 0.108 ${\mathrm{cm}}^{-1\mathrm{}}$.