Spatial distribution of radiation intensity in sources for atomic absorption spectrometry

Abstract

The spatial distribution of the intensity of radiation from LK-2 two-discharge lamps and LD-2 deuterium and halogen lamps, used in atomic absorption spectrometry, has been investigated. It is shown that the distribution of the intensity of radiation from a two-discharge lamp is saddle-shaped and is determined by the joint action of the process of cathode sputtering and of the processes of excitation and ionization of atoms of the filler element under the conditions of a high concentration of electrons in the positive column of the arc discharge. A dome-shaped distribution of radiation intensity with a maximum on the axis of the discharge is characteristic of deuterium lamps and is determined by the distribution of the concentration of electrons in the positive arc column. For halogen lamps, the intensity distribution in the form of a sharp asymmetric peak is determined by the location and dimensions of the luminescent body made in the form of a spiral. The influence of the spatial characteristics of the radiation from the sources on the error in measuring atomic absorption by a space-integrating recording system has beeb evaluated for different radiation intensity distributions. It is shown that this error is negative and reaches a maximum value for a saddle-shaped distribution of the intensity of transilluminating radiation.