In the hybrid structure of both nanostars and J-aggregates, the pronounced dip at 590 nm (which corresponds to the absorption see more wavelength of the J-aggregates) appears as a result of strong coupling of the excited states of J-aggregates and plasmon modes of the nanostars (Figure 4a, blue curve). The wavelength separation between the two peaks in this spectrum (indicated by arrows in Figure 4) is 61 nm, giving the value of Rabi splitting of 213 meV. This value depends on the total absorbance or, in other words, on the concentration of J-aggregates [27], which, for cyanine dye molecules used in this

work, can be influenced by the addition of charged polyelectrolytes [28]. This is selleck chemicals llc demonstrated in Figure 4a (green curve), where positively charged polyelectrolyte PEI has been added to gold nanostars and to the JC1 molecules. As a result, Rabi splitting energy increased to 260 meV, which is 13% of the total transition

energy (which corresponds to spectral position of the dip), indicating the strong coupling regime between the plasmons www.selleckchem.com/products/epz004777.html and the J-aggregate excitons. To demonstrate the advantage of using Au nanostars for the strong coupling with J-aggregates, it would be instructive to compare the values of the achieved Rabi splitting with that of a hybrid system consisting of J-aggregates and gold nanorods [29] of similar volume as nanostars. Based on the TEM image (Figure 2), the effective volume of nanostars was estimated approximating their inner core part by a sphere to which the spikes are attached. The absorption spectrum of Au nanorods used here (Figure 4b, violet curve) exhibits two main resonances: the red-shifted peak at 766 nm corresponds to the longitudinal surface plasmon resonance, whereas the spectral position of the two other bands spanning over the region between 450 and 650 nm is consistent with the wavelengths of the transverse plasmon modes. The absorption band of J-aggregates of JC1 dye (Figure 4c) falls within the spectral region

of the blue-shifted band of the nanorods. In the hybrid system of Au nanorods and J-aggregates, which was fabricated in a similar fashion as that of the gold nanostars, a dip at 595 nm (Figure 4b, cyan curve) with Rabi splitting of 185 meV is observed, which is a much Endonuclease smaller value than that demonstrated above for the nanostar-based hybrid system. Large number of localized plasmon modes in Au nanostars available for coherent coupling with integrated emitters provides the possibility to observe multiple Rabi splitting for the hybrid system where two (or more) different J-aggregate emitters are strongly coupled to gold nanostars. To demonstrate this possibility, we developed a more complex hybrid system integrating nanostars with J-aggregates of not only JC1 but also S2165 dye, whose absorption band is centered at 637 nm, and thus, more than 30 nm red-shifted with respect to the absorption band of JC1 J-aggregates (Figure 5).