of 1 is more stable than the singlet state; b) 1 is more stable than two monomeric CS molecules. loo 1 I,,, [%I m/z Fig. 3. CA mass spectrum of C&', generated by the sequence C2S?' C z S L C2S?" products
In view of the high yields of C2S2 in the neutralization step 4-1 we have carried out a further experiment. The ion with m / z 88 (C,S:") generated in the sequence C,S':"-C,S,+C,S~" was subjected, with the help of the electric sector E (Scheme 1) to a kinetic energy analysis, and the interference-free C, S:" beam (8 keV kinetic energy) was re-excited in the third field-free region in a collision experiment with helium (80% 73. A CA mass spectrum thus obtained (Fig. 3) basically contains no contributions from reionized neutral particles (N), which, e.g., occur in the reaction C2Sq0+fragment ion + N and can lead to an uncertainty in the interpretation of ordinary NRmass spectra. The spectrum reproduced in Figure 3 is free of these possible interferences and it is unambiguous, since it contains the characteristic fragments for 4 with the correct relative intensities (cf. Fig. la).
Summarizing, it can be established that Schaefer's prognosisl'' ".._ we are convinced that C2S2 is a "makeable" molecule . . ." has been verified by the NRMS investigations described here. Obviously other exotic molecules, e.g. the hitherto unknown dimer of carbon monoxide"] or the only partly investigated molecules of the type X(C),Y (X, Y : free electron pairs, H2, 0, S; n=2, 3, 4 etc.)["] related to C2Sz and C202, which are of interest in astrochemistry, as well as many other transients "produced" by Hans Bock and his co-workers,'"' are also possibly detectable by NRMS.