Fluorescence emission spectra fluorene

Steadily in the order 359, 385, 395, and 402 nm. The emission spectra exhibit a clearer vibrational fine structure than the absorption spectra. For spiro-sexiphe-nyl, 35b, a detailed analysis shows that the vibrational splitting of 0.20 eV corresponds to a phenyl breathing mode in the Raman spectrum [108]. If for spiro-sexiphenyl the outer biphenyl moieties are fixed parallel as in 4-Spiro (43), the absorption maximum is shifted from 346 to 353 nm (amorphous films) and the fluorescence maximum from 420 to 429 nm, maintaining the Stokes shift. The corresponding spectra are shown in Figure 3.17. The absorption signal at 310 nm in the spectrum of 43 can be attributed to the terminal fluorene moieties. The quantum yields for the fluorescence in the amorphous film are 38% for 35b and as high as 70 10% for 43 [89]. 

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