Reactions of Cationic Silicon Clusters With Xenon Difluoride.

Cationic silicon clusters, Si + above (1-7) were observed to react bimolecularly and exothermically with xenon difluoride in the ion trap of a Fourier transform mass spectrometer. Analogous to bulk silicon, xenon difluoride "etches" cationic silicon clusters, Si + above a. The etch products are SiF sup + or SiF sub 2, along with a smaller neutral or cationic silicon cluster, Si sub (a-1) whereas for bulk silicon SiF sub 4 has been reported to be the dominant etch product. The observed products result from mono- or di-fluorination of the clusters by xenon difluoride with immediate fragmentation. By extrapolation, xenon difluoride should difluorinate bulk silicon exclusively.