Instrumental Corrections in Measurements of Gas Dispersion. A Three-Slit Problem*

Instrumental corrections have been worked out for a gas refractometer of the hollow prism type used in conjunction with a monochromator. Three slits are involved: entrance slit of the monochromator; exit slit of the monochromator, which is also the entrance slit of the refractometer; and exit slit of the refractometer. The treatment constitutes an extension of the familiar slit and aperture correction procedures that have been worked out for a monochromator alone. The specific objective is the accurate determination of the absolute strengths and widths of individual lines in the refraction spectrum of gases. An example is given of this application.