Knowledge Bank

“A new apparatus for Raman speetroscopy of gases will be described. The Raman tube is 24 ft, in length, and is in two 10 ft, glass sections, six inches in diameter. Illumination is from four water-cooled mercury lamps 10 ft. long, of a design previously $described.1$ The spectrograph is a plane grating instrument in a Littrow arrangement, using an f/10 off-axis paraboloidal mirror. The 5x8 inch grating has 1200 lines per mm., and in the third order a dispersion of about $6cm-1$ per mm, at 4358A. A nine-fold gain in intensity without any loss of resolution is obtained by means of a cylindrical lens in front of the plateholder. The Q branches of the oxygen and nitrogen fundamentals have been resolved; these and other preliminary results will be discussed.”