  Plasmonic nanocrystals with hot spots are able to localize optical energy in
small spaces. In such physical systems, near-field interactions between
molecules and plasmons can become especially strong. This paper considers the
case of a nanoparticle dimer and a chiral biomolecule. In our model, a chiral
molecule is placed in the gap between two plasmonic nanoparticles, where the
electromagnetic hot spot occurs. Since many important biomolecules have optical
transitions in the UV, we consider the case of Aluminum nanoparticles, as they
offer strong electromagnetic enhancements in the blue and UV spectral
intervals. Our calculations show that the complex composed of a chiral molecule
and an Al-dimer exhibits strong CD signals in the plasmonic spectral region. In
contrast to the standard Au- and Ag-nanocrystals, the Al system may have a much
better spectral overlap between the typical biomolecule's optical transitions
and the nanocrystals' plasmonic band. Overall, we found that Al nanocrystals
used as CD antennas exhibit unique properties as compared to other commonly
studied plasmonic and dielectric materials. The plasmonic systems investigated
in this study can be potentially used for sensing chirality of biomolecules,
which is of interest in applications such as drug development.
