Appearance potential measurements.

Two techniques for the measurement of appearance potentials on an A.E.I. M.S.9 Mass Spectrometer have been developed. The first was similar to that described by Galegos and Klaver and was used in the measurement of the molecular ionisation potentials of some 1,5 cyclo- octadiene rhodium halogen complexes, (CODRhX)2, and the appearance potential of 1,5 cyclooctadiene from these compounds. The second technique utilized magnetic scanning in an attempt to obtain results of greater accuracy than those obtained using the first technique which involved scanning the ion accelerating voltage. The second technique also included recording of the data directly on to paper tape facilitating the treatment of the data using computers. Using this technique appearance potentials were measured from organosilicon compounds enabling Si - X (where X = Si, C, H, O, C1) bond dissociation energies and standard heats of formation to be calculated.