“…From T n the dye can efficiently cross back to the singlet system, where fluorescence emission occurs 17–20. ReISC has previously been shown for dyes with high ISC yields such as bipyridien,17 erythrosine B,18, 21, 22 rose bengal,18, 21–25 cyanine dyes,19, 20 anthracene,26 eosin Y21, 22 and propiophenone 27. ReISC had to be included in fluorescence statistics of single‐molecule experiments of sulforhodamine 101 or DiI in polymethylmethacrylat (PMMA),28 terrylene in p ‐terphenyl crystals,29 merocyanine 540 in solution,30 and of cyanine 5 (Cy5) in poly(vinyl‐alcohol) (PVA),31 on air‐glass interfaces,32 under nitrogen atmosphere33 or in Förster resonance energy transfer (FRET) experiments 34.…”