A Deep Learning Approach for Meter-Scale Air Quality Estimation in Urban Environments Using Very High-Spatial-Resolution Satellite Imagery.

High-spatial-resolution air quality (AQ) mapping is important for identifying pollution sources to facilitate local action. Some of the most populated cities in the world are not equipped with the infrastructure required to monitor AQ levels on the ground and must rely on other sources, like satellite derived estimates, to monitor AQ. Current satellite-data-based models provide AQ mapping on a kilometer scale at best.

Infrared Open Cavities for Strong Vibrational Coupling.

Arrays of subwavelength plasmonic nanoparticles exhibiting narrowband lattice resonances are referred to as open cavities because of their ability to strongly couple with electronic excitations in molecular chromophores. However, realization of these ideas in the mid-infrared spectral region has been limited. We demonstrated a dramatic reduction in the bandwidth of lattice resonances in large-area arrays of half-wavelength mid-infrared antennas, reaching resonance quality factors above 200.

Probing the role of oscillator strength and charge of exciton forming molecular J-aggregates in controlling nanoscale plasmon-exciton interactions.

In this study, we probe into the roles of exciton oscillator strength and charge of J-aggregates as well as nanoparticle's surface capping ligands in dictating the plasmon-exciton interaction. We systematically compare the plasmon-exciton coupling strengths of two hybrid plexcitonic systems involving CTAB-capped hollow gold nanoprisms (HGNs) and two different cyanine dyes, TDBC and PIC, having very similar J-band spectral positions and linewidths, but different oscillator strengths and opposite charges. Both HGN-PIC and HGN-TDBC systems display large Rabi splitting energies which are found to be extremely dependent on dye-concentrations.

Exploring the coherent interaction in a hybrid system of hollow gold nanoprisms and cyanine dye J-aggregates: role of plasmon-hybridization mediated local electric-field enhancement.

In this work, we probed the possibility of observing strong plasmon-exciton interactions in hollow gold nanoprism-J-aggregate nanocomposites. Several different hollow gold nanoprisms (HGNs) with different aspect ratios were synthesized. This allowed us to systematically tune the LSPR energies through the exciton energy of the PIC-J-aggregate, which in turn allowed us to have direct determination of the coupling strength of HGN-J-aggregate composites.

Large second harmonic generation from hollow gold nanoprisms: role of plasmon hybridization and structural effects.

The structure and morphology of nanomateials strongly influence their nonlinear optical properties. In this work, we report a systematic investigation of second order nonlinear optical responses and their structural dependencies in the case of a plasmonically hybrid nanostructure, hollow gold nanoprisms (HGNs). The first hyperpolarizabilities (β) of the HGNs have been measured using the two-photon Rayleigh scattering (TPRS) technique.