ELECTRONICALLY MODULATED MICROWAVE-EXCITED ELECTRODELESS DISCHARGE TUBES AS SOURCES IN ATOMIC ABSORPTION SPECTROSCOPY

Electronic modulation of a selected range of electrodeless discharge tubes is achieved by superimposing a 50 Hz component on the d.c. potential of the anode of the magnetron valve. The effect of modulation is favourable and the usual methods of tube preparation are satisfactory. The source spectra for lead, mercury, silver, thallium and tin are compared with those for the corresponding hollow-cathode lamps and the analytical atomic absorption working curves obtained with the various sources are compared. The sources for lead and tin give considerably higher sensitivity and a wider working range than the hollow-cathode lamps because of the absence of continuous background or non-absorbing lines near the resonance line. The mercury source behaves similarly, probably because of less self-reversal. © 1969.