Thorium Lamps and Interferometrically Measured Thorium Wavelengths

Abstract

Wavelengths emitted from an electrodeless thorium iodide lamp are compared with those emitted by water-cooled and liquid-nitrogen-cooled hollow-cathode lamps. Three hundred forty six thorium lines have been interferometrically measured, using a hollow-cathode lamp as a source, in the range from 4574 to 6676 Å. The accuracy of the measurements has been tested using the combination principle, and was found to be one part in 6 to 9.5 × 107.