Photon emitters placed in an optical cavity experience an environment that changes how they are coupled to the surrounding light field. In the weak-coupling regime, the extraction of light from the emitter is enhanced. But more profound effects emerge when single-emitter strong coupling occurs: mixed states are produced that are part light, part matter1, 2, forming building blocks for quantum information systems and for ultralow-power switches and lasers. Such cavity quantum electrodynamics has until now been the preserve of low temperatures and complicated fabrication methods, compromising its use. Here, by scaling the cavity volume to less than 40 cubic nanometres and using host–guest chemistry to align one to ten protectively isolated methylene-blue molecules, we reach the strong-coupling regime at room temperature and in ambient conditions. Dispersion curves from more than 50 such plasmonic nanocavities display characteristic light–matter mixing, with Rabi frequencies of 300 millielectronvolts for ten methylene-blue molecules, decreasing to 90 millielectronvolts for single molecules—matching quantitative models. Statistical analysis of vibrational spectroscopy time series and dark-field scattering spectra provides evidence of single-molecule strong coupling. This dressing of molecules with light can modify photochemistry, opening up the exploration of complex natural processes such as photosynthesis and the possibility of manipulating chemical bonds.

Single-molecule strong coupling at room temperature in plasmonic nanocavities

The experimental data taken in the NanoPhotonics Group at the Cavendish Laboratory (University of Cambridge), collected between 01/10/2014 to 01/02/2016. Simulations performed at the Blackett Laboratory, Department of Physics (Imperial College, London) and at the Department of Chemistry (King’s College London). Dataset for accepted journal article "Single-molecule strong coupling at room temperature in plasmonic nanocavities"

Research data supporting "Single-molecule strong coupling at room temperature in plasmonic nanocavities"

Calculation of the thermodynamic and transport properties of aqueous species at high pressures and temperatures: Standard partial molal properties of organic species

Cyclodextrins: structure, physicochemical properties and pharmaceutical applications

Ionic liquids (ILs) and deep eutectic solvents (DESs) have been suggested as eco-friendly alternatives to organic solvents. A trace amount of water is often unavoidable as impurity, and water is also added on purpose to reduce their problematically high viscosity and lower their high price. Understanding the distinct effects of water on the properties of ILs/DESs is highly important. In this review, we collect published experimental and theoretical results for IL/DES–H2O systems at varied water concentrations and analyze them. Results from mechanistic studies, thermodynamic modelling and advanced experiments are collected and critically discussed. Six commonly studied IL/DES–H2O systems were selected to map experimental observations onto microscopic results obtained in mechanistic studies. A great variety of distinct contours of the excess properties can be observed over the entire compositional range, indicating that the properties of IL/DES–H2O systems are highly unpredictable. Mechanistic studies clearly demonstrate that the added H2O rapidly changes the heterogeneous 3D structures of pure ILs/DESs, leading to very different properties and behaviour. There are similarities between aqueous electrolytes and IL/DES solutions but the bulky and asymmetric organic cations in ILs/DESs do not conform to the standard salt dissolution and hydration concepts. Thermodynamic modelling previously assumes ILs/DESs to be either a neutral ion-pair or completely dissociated ions, neglecting specific ion hydration effects. A new conceptual framework is suggested for thermodynamic modelling of IL/DES–H2O binary systems to enable new technologies for their practical applications.

/pdf/the-peculiar-effect-of-water-on-ionic-liquids-and-deep-2hscgp3hx0.pdf

The peculiar effect of water on ionic liquids and deep eutectic solvents

The self-aggregation of Methylene Blue [MB] (1×10−6–4×10−4 M) in water and in aqueous solutions of
 Bu4NBr (0.1–0.3 M) and urea (0.1–4 M) has been investigated by recording electronic spectra in the wavelength range 550 to 700 nm. Analysis of the spectral data yielded the dimer dissociation constant, and individual characteristic monomer and dimer spectra. By applying the exciton model for the first time, the interaction energy between the MB molecules in the dimer species has been evaluated. Further, information about the dimer geometry and the twist angle between the dipoles of the MB molecules in the dimer species has
 been obtained. Similar data have also been obtained for solutions of MB in aqueous urea and Bu4NBr solutions. The significant observation is the change in the dimer geometry from sandwich type to end-on-end type in
 the presence of urea and Bu4NBr. It is observed that the contribution to the interaction energy is mainly from
 van der Waal's type and dispersion forces, in addition to short-range forces involving multipoles. However, the contribution from hydrogen-bonding interactions between MB and water molecules is found to be significantly low. It is proposed that water structural effects and hydrophobic interactions are
 the major factors in the phenomenon of aggregation.

Self-aggregation of Methylene Blue in aqueous medium and aqueous solutions of Bu4NBr and urea

Experimental measurements of density at different temperatures ranging from 293.15 to 313.15 K, the speed of sound and osmotic coefficients at 298.15 K for aqueous solution of 1-ethyl-3-methylimidazolium bromide ([Emim][Br]), and osmotic coefficients at 298.15 K for aqueous solutions of 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) in the dilute concentration region are taken. The data are used to obtain compressibilities, expansivity, apparent and limiting molar properties, internal pressure, activity, and activity coefficients for [Emim][Br] in aqueous solutions. Experimental activity coefficient data are compared with that obtained from Debye−Huckel and Pitzer models. The activity data are further used to obtain the hydration number and the osmotic second virial coefficients of ionic liquids. Partial molar entropies of [Bmim][Cl] are also obtained using the free-energy and enthalpy data. The distance of the closest approach of ions is estimated using the activity data for ILs in aqueous solutions a...

/pdf/thermodynamic-studies-of-ionic-interactions-in-aqueous-4jho9kujf1.pdf

Thermodynamic studies of ionic interactions in aqueous solutions of imidazolium-based ionic liquids [Emim][Br] and [Bmim][Cl].

http://path.web.ua.pt/file/j.jct.2007.10.007.pdf

Acoustic and volumetric properties of aqueous solutions of imidazolium based ionic liquids at 298.15 K

The osmotic coefficients and densities of aqueous and CCl4 solutions involving 18-crown-6 (18C6) as solute in the concentration range 0.1 to 2.0 m at 25 °C were measured. The data obtained is used to calculate activities of solvent and activity coefficient of solute and solvent at 25 °C as a function of concentration. It has been observed that activity coefficient of 18C6 increases with increase in concentration of 18C6 while the reverse is true for CCl4 solutions. Using the partial molar volume of the solute at infinite dilution, the solute−solvent cluster integral values were evaluated which yielded information on solute−solvent interaction. Application of McMillan-Mayer theory enabled us to obtain second and third virial coefficients for solute, which have been decomposed into attractive and repulsive contributions to solute−solute interactions. These are compared with other solutes such as sucrose, glucose, urea, etc. On the basis of attractive and repulsive contributions to solute−solvent and solute−...

Kesharsingh J. Patil

Papers

Self-aggregation of Methylene Blue in aqueous medium and aqueous solutions of Bu4NBr and urea

Thermodynamic studies of ionic interactions in aqueous solutions of imidazolium-based ionic liquids [Emim][Br] and [Bmim][Cl].

Acoustic and volumetric properties of aqueous solutions of imidazolium based ionic liquids at 298.15 K

Studies of Osmotic and Activity Coefficients in Aqueous and CCl4 Solutions of 18-Crown-6 at 25 °C

Thermodynamic studies for aqueous solutions involving 18-crown-6 and alkali bromides at 298.15 K