Mass Spectrometric Study of Some Polycarbide Species Formed in the Vacuum Spark Discharge

The relative abundances of several MCn polycarbide molecular ions (with a metal atom M) formed in the vacuum spark have been measured. It has been found that the abundance distribution patterns -in the range of n = 1 to 14 or more- are similar to those of the Cn carbon molecules. In particular, this similarity is very close in the case of the LaCn+ and Cn+1+ ions on the one hand, and in the case of the SiCn+, BCn+ and Cn- ions, on the other. In view of these results the structure of the LaCn and Cn molecules may be regarded as nearly identical, while in the case of the SiCn and BCn polycarbides, M+-Cn- type polarized molecules are assumed.