Electronic spectroscopy of a cold SiO${}^{+}$ sample: Implications for optical pumping

The dispersed fluorescence following pulsed dye laser excitation of the ${\text{B}}_2{\mathrm{\Sigma }}^{+}-{\text{X}}^2{\mathrm{\Sigma }}^{+}(0,0)$ band of a cold sample of SiO${}^{+}$ has been recorded and analyzed. The branching ratios for $$\text{B}$_2 \Sigma^+ (v=0) \rightarrow $\text{X}$^2 \Sigma^+(v)$and$$\text{B}$_2 \Sigma^+ (v=0) \rightarrow $\text{A}$^2 \Pi_i(v)$ emission were determined and compared with values predicted based upon existing experimental and theoretical data. The experimentally determined branching ratios show that the $$\text{B}$_2 \Sigma^+ (v=0) \rightarrow $\text{X}$^2 \Sigma^+(v)$ transitions are somewhat less diagonal than predicted. The implications for laser cooling of a trapped sample of SiO${}^{+}$ using broadband laser excitation are discussed.