Clusters of metal atoms at a fixed size can assume different structural arrangements, known as isomers, which may have nearly the same energy. Therefore at given experimental conditions distribution of these isomers can be present. While the size selection is a relatively common technique, the isomer selection is not; it is therefore more difficult to obtain information about a single isomer. We report here on isomer specific spectroscopy of Ag9 clusters together with ab initio calculations allowing to identify the isomer responsible for the measured excitation pattern and fluorescence.