In Fig. 5, seven representative UV/vis spectra are shown. The spectra agree well with those of pure H-aggregates (Auweter et al. 1999). However, the original sample contained J-aggregates too (Fig. 1, dashed line). We believe that the J-aggregates were already precipitated before the first scan in the AUC cell was taken. Indeed precipitation of particulate material inside the reservoir of the vinograd cell was observed visually after cell disassembly following the experiment. However, irrespective of the actual nature of the particulate material that remained in the Vinograd cell reservoir, the result stands for itself that the coloristic polydispersity (Fig. 1) is not due to an intra-particle but inter-particle distribution of morphologies (Fig. 6). This result is contrary to the previous assumption that is sketched in Fig. 2, where H/J-aggregates would coexist in the particles.
Fig. 6 Ad hoc structural model of the β-carotene microparticle system on basis of the presented AUC results. The different color of the samples does not originate from the intraparticular coexistence of H- and J-aggregates as assumed before (Fig. 2) (Auweter et al. 1999) but instead separate particles contain pure H- or J-aggregates and the concentration ratio between these particles determines the colour of the final sample. Note the difference to Fig. 2