Electronic spectroscopy of the CaCCCH3 and SrCCCH3 free radicals
Abstract
The first spectroscopic observation of the free radicals CaCCCH3 and SrCCCH3 is reported. Vibrationally-resolved laser-induced
2A1 and
2A1–
2A1 electronic transitions. The vibrational structure in each system is limited to a short progression in the metal–carbon stretching mode. The Ö
origin is blue-shifted relative to the monoacetylides of Ca and Sr. Furthermore, in contrast to CaCCH and SrCCH, where predissociation seems to reduce the fluorescence quantum yield to near zero, the
states of both CaCCCH3 and SrCCCH3 show strong fluorescence. Although relatively remote from the
state out of the predissociative region.