The Observation of Extraphotographic Infrared Atomic Emission Spectra

The extension of observation of atomic line emission spectra into the extraphotographic infrared region by high-resolution methods has been accomplished by procedures now well established but which have not found widespread application. Owing to the nonintegrating character of radiometric detecting devices, the observations are always energy-limited. This handicap may be overcome by a threefold approach: utilization of a fast optical system; optimizing the detecting and amplifying system; and developing sources of maximum energy output consistent with the character of the spectrum to be studied. Successful systems for use with a high-resolution grating spectrometer are described. Examples are given of the extension of the observation of several spectra to a fairly easily attainable limit of 4 μ by use of lead sulfide detectors designed for liquid nitrogen cooling.