On the Temperature-Dependence of the Long Wavelength Fluorescence and Absorption of Rhodopseudomonas viridis Reaction Centers

Recent measurements of absorbance and fluorescence spectra of reaction centers of photosynthetic bacteria indicate that lowering the temperature induces a significant narrowing and red shift of the long wavelength dimer band, whereas the positions of all the other absorption bands are unaffected. This phenomenon has been observed in absorbance /1, 2/ and emission /1/ spectra (300 K, 77 K) of reaction centers of Rp. sphaeroides. Reaction centers of Rp. viridis behave similarly when comparing absorbance spectra at various temperatures between 300 K and 2 K /3–6/, magnetooptical absorbance difference spectra at 285 K and 115 K /7/ and fluorescence spectra at 77 K /6/ and 2 K /6, 8/.