Formation of long-lived CDn2+ and CHn2+ dications

A systematic study of the formation of CDn2+ and CHn2+ dications in fast ch arge-stripping collisions with Ar atoms was conducted. The experimental met hod was based on the detection of the D (or H) fragments of the molecular i on of interest, and thus reducing the effect of the fraction of molecular i ons containing the C-13 isotope and other beam impurities. We observed long -lived CD22+, CD42+, and CD52+ dications. In the same process neither long- lived CD2+ nor CD32+ were observed. The mean lifetime of CD22+ was determin ed to be 4.0 +/- (1.3)(1.1) mu s, and those of CD42+ and CD52+ were longer than 2.1 and 3.3 mu s, respectively. The production cross sections of CDn2 from different CDm+ beams were measured. Long-lived CD22+ was formed from all CDm+ beams (m greater than or equal to 2) and also directly from the rf ion source. In contrast, CD42+ and CD52+ were formed only from CD4+ and CD 5+ respectively.