Figure 7.
Photooxidation and photodegradation of all-trans-retinal dimer. Analysis by electrospray ion multi-mode ionization (ESI). Samples of all-trans-retinal were unirradiated (A) or irradiated (B) at 430 nm (hv). The series of peaks from m/z 551–679 reflect photooxidation at carbon-carbon double bonds in all-trans-retinal dimer. Lower mass peaks (< m/z 592) correspond to all-trans-retinal dimer photodegradation products. C. Proposed structures of the largest of the photodegradation products. Upper left, all-trans-retinal dimer exhibits absorbance peaks at 432 nm and 292 nm that can be assigned to long and short arms of the molecule, respectively.