Metal-enhanced S2 fluorescence from azulene

In this Letter, we report the first observation of metal-enhanced S2 emission at room and low temperature (77 K). The S2 emission intensity of azulene is enhanced by close proximity to silver island films (SiFs). In this regard, a ≈2-fold higher S2 fluorescence intensity of azulene was observed from SiFs as compared to a glass control sample. This suggests that S2 excited states can couple to surface plasmons and enhance S2 fluorescence yields, a helpful observation in our understanding the interactions between plasmons and lumophores, and our continued efforts to develop a unified plasmon-lumophore/fluorophore theory.