A New Source for Infra-Red Spectrometers

A new source for infra-red spectrometers consisting of a carbon rod heated electrically in vacuum is described. Readily obtainable, such a rod may easily be machined or ground to various sizes and shapes. Ground with a V-shaped cavity one inch long in the center, a 6-mm diameter rod has been operated at a temperature of 1800°C with a power consumption of 600 watts and a lifetime of the order of 100 hours. Its emissive power is about the same from 1–10μ as that of a Globar at the same temperature while beyond 10μ it is considerably greater. The rod thus provides a source whose brightness is comparable with that of a Nernst glower but which may be made of greater width and which is much less delicate and easily burned out.