The [17.0] 2Π1/2←X 2Π1/2 system of AlCa

Laser-induced fluorescence spectroscopy has been used to study supersonically cooled AlCa. This study investigates under higher resolution (0.007 cm-1) a single band previously studied and tentatively assigned as the (0-0) vibrational transition of the [17.0] 2Δ3/2(?)←X 2Π1/2 system of AlCa. The resolution of the rotational structure in the present study enabled a definite assignment as a 2Π1/2←2Π1/2 transition. Analysis of the spectrum gives B0′=0.096685(19) cm-1, (p+2q)′=−0.013078(370) cm−1, and B0″=0.105518(20) cm-1. These convert to ground and excited state bond lengths of r0″=3.14942(30) and r0′=3.29014(32) Å, respectively.