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A novel method is proposed to directly characterize the exciton‐plasmon coupling in a photosensitive nanoparticle‐on‐mirror (NPoM) nanocavity. Under the illumination of UV light, the localized surface plasmon resonance (LSPR) peaks of the nanocavity can be continuously tuned over a wide range (≈65 nm), enabling precise determination of the energy dispersion relationship of plexcitons in the nanocavity. The results indicate that the energy of Rabi splitting can be actively tuned from 65 meV (weak coupling) to 170 meV (strong coupling) by adjusting the LSPR peak of a specific nanocavity (particle size L≈55‐92 nm) to the exciton wavelength (the zero detuning). In addition, the criterion of strong coupling is optimized by introducing single‐particle absorption spectroscopy. The work offers an intuitive method for the strong coupling characterization in nanocavity, paving the way for the real‐time tuning of coupling strength over a wide range (100 meV) from weak to strong coupling regimes. [ABSTRACT FROM AUTHOR]

The laser‐irradiated aerosolized nanostructures with complex geometries offer unique opportunities to steer orientation‐dependent photoion emission for multiple applications of directional ion sources and photocatalysis. The orientation‐dependent photoion emission is characterized by measuring the distribution and probability on differently oriented nanostructures. This unique capability is achieved by introducing momentum‐to‐space orientation discrimination in the single‐shot velocity map imaging technique with the aerodynamic lens. The effect of geometry, polarization, and concentration to control the photoion emission from differently oriented nanostructures is introduced for optimizing the potential applications of photoion emission including directional tunable nanoanode and optical sensors. The mechanism behind controlling the photoion emission is visualized by the variations in the regions of high laser intensity inside the nanostructures responding to the orientation, geometry, and polarization. This work represents an advance in characterizing the photoion emission from the randomly oriented aerosolized nanostructures and facilitates the potential for combining with the pump–probe methods to provide an intuitive understanding of their real‐time ionization dynamics. [ABSTRACT FROM AUTHOR]