- Sadegh, Sanaz;
- Yang, Mu-Han;
- Ferri, Christopher GL;
- Thunemann, Martin;
- Saisan, Payam A;
- Wei, Zhe;
- Rodriguez, Erik A;
- Adams, Stephen R;
- Kiliç, Kivilcim;
- Boas, David A;
- Sakadžić, Sava;
- Devor, Anna;
- Fainman, Yeshaiahu
Non-degenerate two-photon excitation (ND-TPE) has been explored in two-photon excitation microscopy. However, a systematic study of the efficiency of ND-TPE to guide the selection of fluorophore excitation wavelengths is missing. We measured the relative non-degenerate two-photon absorption cross-section (ND-TPACS) of several commonly used fluorophores (two fluorescent proteins and three small-molecule dyes) and generated 2-dimensional ND-TPACS spectra. We observed that the shape of a ND-TPACS spectrum follows that of the corresponding degenerate two-photon absorption cross-section (D-TPACS) spectrum, but is higher in magnitude. We found that the observed enhancements are higher than theoretical predictions.