We investigate the chemical reactivity of molecular populations confined inside a nanofluidic Fabry-Pérot cavity. Due to strong light-matter interactions developing between a resonant electromagnetic cavity mode and the electric dipole moment of the confined molecules, a collective polariton excitation is formed. The former gets dressed by environmental vibrational and rotational degrees of freedom of the solvent. We call the resulting polariton dressed by its cloud of environmental excitation a “reacton”, since it further undergoes chemical reactions. We characterize how the reacton formation modifies the kinetics of a photoisomerization chemical reaction involving an elementary charge-transfer process. We show that the reaction driving force and reorganization energy are both modulated optically by the reactant concentration, the vacuum Rabi splitting, and the detuning between the Fabry-Pérot cavity frequency and targeted electronic transition. Finally, we compute the ultrafast picosecond dynamics of the whole photochemical reaction. We predict that despite optical cavity losses and solvent-mediated nonradiative relaxation, measurable signatures of the reacton formation can be found in state-of-the-art pump-probe experiments.

We recently assisted in a revolution in the realm of fluorescence microscopy triggered by the advent of super-resolution techniques that surpass the classic diffraction limit barrier. By providing optical images with nanometer resolution in the far field, super-resolution microscopy (SRM) is currently accelerating our understanding of the molecular organization of bio-specimens, bridging the gap between cellular observations and molecular structural knowledge, which was previously only accessible using electron microscopy. SRM mainly finds its roots in progress made in the control and manipulation of the optical properties of (single) fluorescent molecules. The flourishing development of novel fluorescent nanostructures has recently opened the possibility of associating super-resolution imaging strategies with nanomaterials’ design and applications. In this review article, we discuss some of the recent developments in the field of super-resolution imaging explicitly based on the use of nanomaterials. As an archetypal class of fluorescent nanomaterial, we mainly focus on single-walled carbon nanotubes (SWCNTs), which are photoluminescent emitters at near-infrared (NIR) wavelengths bearing great interest for biological imaging and for information optical transmission. Whether for fundamental applications in nanomaterial science or in biology, we show how super-resolution techniques can be applied to create nanoscale images “in”, “of” and “with” SWCNTs.

We study theoretically the emission and lasing properties of a single nanoshell spaser nanoparticle with an active core and a plasmonic metal shell. Using time‐dependent equations for the gain medium and metal, we calculate the lasing threshold through an instability analysis. Below threshold, the nanoshell acts as an optical amplifier when excited by an external probe field, while above threshold, it enters a regime of autonomous lasing. At the gain threshold, the lasing starts at one frequency, typically a plasmon resonance of the nanoparticle. With increasing gain, the emission then broadens to additional frequencies. This result contrasts with previous findings reporting only a single emission wavelength above threshold. We also compute the full spectrum and linewidth of the nanolaser, revealing strong frequency shifts and an asymmetrical lineshape. Finally, we demonstrate that the emission line can be tuned across the visible spectrum by modifying the aspect ratio of the nanoshell.