Atoms and molecules often react at different rates depending on their internal quantum
states. Thus, controlling which internal states are populated can be used to manipulate the
reactivity and can lead to a more detailed understanding of reaction mechanisms. We
demonstrate this control of reactions by studying the excited state reaction reaction Ca $^+
$+ O $ _2 $$\rightarrow $ CaO $^+ $+ O. This reaction is exothermic only if Ca $^+ $ is in
one of its excited electronic states. Using laser-cooling and electrodynamic trapping, we cool …

Atoms and molecules often react at different rates depending on their internal quantum
states. Thus, controlling which internal states are populated can be used to manipulate the
reactivity and can lead to a more detailed understanding of reaction mechanisms. We
demonstrate this control of reactions by studying the electronically excited state reaction C
a++ O 2→ C a O++ O. This reaction is exothermic only if Ca+ is in one of its excited
electronic states. Using laser-cooling and electrodynamic trapping, we cool and trap Ca+ at …