Fig. 5. Concentration-corrected CD spectra of the helix-inverted product 3 using (A) CP 355 nm (100 mW) or plane polarized 355 nm (100 mW) + CP 532 nm (50 mW) or (B) combinations of CP 355 nm (100 mW) and CP 532 nm (50 mW) in short burst (10 s) irradiation to establish the PSS between 1 and 2 before allowing the thermal helix inversion. The magnitude of the CD peaks corresponds linearly to the enantiomeric excess of 3 in the sample and, hence, of that of 2 in the PSS. The arrows next to RCP/LCP in (A) indicate the direction of propagation of the electric vector of the CP light in time looking towards the source.
