THERMAL-DISSOCIATION SURFACE-IONIZATION OF ORGANOMETALLIC COMPOUNDS ON THE HEATED RE-OXIDE SURFACE - CARBONYLS OF FE, CR, MN AND CO, ACETYLACETONATE COMPLEXES OF AL, V, CR AND ZR, AND LITHIUM AMIDES

The gas/solid phase ionization process has been investigated for carbonyls of Fe(CO)5, Cr(CO)6, CO2(CO)8 and Mn2(CO)10, for acetylacetonate complexes of Al, V, Cr, and Zr, and for two lithium amides. The study was made under the conditions that these molecules from a vapor are supplied to the incandescent rhenium-oxide emitter. Ionization on the Re-oxide emitter yields the corresponding ion species containing the metal atom with high efficiency except for the lithium amides. The results indicate a thermal dissociation/ionization process; the overall process is dominated by thermal dissociation of the compounds to neutral fragments, followed by ionization of these species. The ionization has been rationalized in terms of the well-known Saha-Langmuir surface ionization equation. The mass spectral results are discussed via comparison of the spectral patterns and the sensitivity of these compounds under thermal dissociation/surface ionization (TD/SI), electron ionization (EI) and multiphoton dissociation/multiphoton ionization (MPD/MPI) techniques.