A MASS-SPECTROMETRIC STUDY OF THE THERMAL-DECOMPOSITION OF SMALL QUANTITIES OF AGNO3, CSNO3 AND CS2CO3

The thermal decomposition of minute quantities of AgNO3, CsNO3 and Cs2CO3 on platinum and on glass-like carbon was studied by use of a mass spectrometer. We observed that AgNO3 decomposed at 700 K and Ag evaporated at T > 1100 K. In contrast, CsNO3 evaporated mainly as molecules. Cs was found to be the main species in the gas flow from a Cs2CO3 filled Knudsen cell lined with glass-like carbon. The appearance potentials of the molecular species were determined as 10.5 eV for Cs-2(+), 7.0 eV for Cs2O+, and 5.6 eV for Cs2CO3+. Platinum catalyzes the decomposition of minute Cs2CO3 quantities to provide mainly cesium. A method for the fast and automatic measurement of appearance potentials was developed.