Atomic and molecular spectra of vapors evolved in a graphite furnace. Part3: alkaline earth fluorides

Slurries of alkaline earth fluorides in aqueous and toluene media, 100 mu g as element, were vaporized in a pyrocoated and Ir-sputtered graphite furna ce during fast heating from 400 to 2500 degrees C. Absorption spectra in th e 200-375-nm range were obtained using a dedicated CCD spectrometer. The va porization of Be, Mg, Ca, Sr and Ba fluorides showed the signs of the evolu tion of the di-fluorides at low temperature followed by the appearance of t he mono-fluorides and atomic vapor. The exothermal interaction of sample Va por with graphite caused the evolution of heat into the furnace gas that su bstantiated light scattering below 400 nm, emission continuum above 400 nm and reversal of some molecular bands into emission. All the thermal effects were displayed more intensely in the presence of the hydrolysis products i n the aqueous slurry. The hydrolysis was suppressed, and the thermal effect s were reduced, when the toluene slurries were used. The vapor interaction with graphite was reduced in a great extent in the Ir sputtered tubes, and hence, the spectra of the mono-fluorides were not affected by the overlappi ng of simultaneous thermal effects. (C) 2000 Elsevier Science B.V. All righ ts reserved.