EXCITATION MODULATION BY WATER - EFFECTS OF DESOLVATION ON LINE-INTENSITIES, TEMPERATURES AND ION - ATOM RATIOS PRODUCED BY INDUCTIVELY COUPLED PLASMAS

Desolvation of a pneumatically generated aerosol reduces water mass transport by a factor of six but leaves nebuliser efficiency and total mass transport virtually unchanged. A survey of both OH band intensity and the intensity ratios of selected lines leads to the conclusion that aerosol water selectively reduces the intensities of atomic and ionic transitions. Lines with excitation potentials below the dissociation energy of water remain unaffected except when observed very low in the plasma directly above the outer torch tube. Atom and ion lines with energies above the bond energies of water are markedly enhanced by desolvation. Ion - atom intensity ratios, and excitation and ionisation temperatures are also affected by aerosol desolvation.