Coherent coupling of molecular resonators with a micro-cavity mode

The optical hybridization of the electronic states in strongly coupled molecule-cavity systems have revealed unique properties such as lasing, room temperature polariton condensation, and the modification of excited electronic landscapes involved in molecular isomerization. Here we show that molecular vibrational modes of the electronic ground state can also be coherently coupled with a micro-cavity mode at room temperature, given the low vibrational thermal occupation factors associated with molecular vibrations, and the collective coupling of a large ensemble of molecules immersed within the cavity mode volume. This enables the enhancement of the collective Rabi-exchange rate with respect to the single oscillator coupling strength. The possibility of inducing large shifts in the vibrational frequency of selected molecular bonds should have immediate consequences for chemistry.Comment: 22 pages, 6 figures (including Supplementary Information file

Multiple Rabi Splittings under Ultra-Strong Vibrational Coupling

From the high vibrational dipolar strength offered by molecular liquids, we demonstrate that a molecular vibration can be ultra-strongly coupled to multiple IR cavity modes, with Rabi splittings reaching $24\%$ of the vibration frequencies. As a proof of the ultra-strong coupling regime, our experimental data unambiguously reveal the contributions to the polaritonic dynamics coming from the anti-resonant terms in the interaction energy and from the dipolar self-energy of the molecular vibrations themselves. In particular, we measure the opening of a genuine vibrational polaritonic bandgap of ca. $60$ meV. We also demonstrate that the multimode splitting effect defines a whole vibrational ladder of heavy polaritonic states perfectly resolved. These findings reveal the broad possibilities in the vibrational ultra-strong coupling regime which impact both the optical and the molecular properties of such coupled systems, in particular in the context of mode-selective chemistry.Comment: 10 pages, 9 figure

Ultra-strong coupling of molecular materials: spectroscopy and dynamics

We report here a study of light–matter strong coupling involving three molecules with very different photo-physical properties. In particular we analyze their emission properties and show that the excitation spectra are very different from the static absorption of the coupled systems. Furthermore we report the emission quantum yields and excited state lifetimes, which are self-consistent. The above results raise a number of fundamental questions that are discussed and these demonstrate the need for further experiments and theoretical studie

An uncommon cause of ascites; spontaneous rupture of biliary cystadenoma

Biliary cystadenomas are cystic hepatic tumors of biliary origin. Cystadenomas are often slow growing benign tumors but always harbor the risk of malignant transformation. Cystadenomas are often asymptomatic but may present with abdominal pain and distension. Though suspected with cross sectional abdominal imaging definitive diagnosis almost always requires histology. Spontaneous rupture of cystadenoma had been reported thrice in medical literature till date, all presenting with peritonitis. We here report a case spontaneous intraperitoneal rupture of biliary cystadenoma presenting as ascites without peritonitis

Surface plasmon coupled circular dichroism of Au nanoparticles on peptide nanotubes

Au nanoparticles grown on D- and L-isomers of diphenylalanine peptide nanotubes showed a bisignated CD signal at their surface plasmon frequency with positive and negative couplets, respectively. The surface plasmon coupled CD signal in these hybrid systems originates from the asymmetric organization of Au nanoparticles on peptide nanotubes. Mirror image relationship in the CD spectra clearly indicates that the chiral molecules on the nanotubes drive the organization of nanoparticles in two different ways

Solvent Dependence on Cooperative Vibrational Strong Coupling and Cavity Catalysis

Strong light-matter coupling offers a unique way to control chemical reactions at the molecular level. Here, we try to compare the solvent effect on a solvolysis process under cooperative vibrational strong coupling (VSC). Two solvents, ethyl acetate and cyclopentanone are chosen to study cavity catalysis by coupling the C=O stretching band of the reactant and the solvent molecules to a Fabry-Perot cavity mode. Interestingly, both the solvent system catalyze the chemical reaction under cooperative VSC conditions. However, the resonance effect on catalysis is observed at different temperatures for the two solvent systems, which is further confirmed by thermodynamic studies. Cavity detuning and other control experiments suggest that cooperative VSC of the solvent plays a crucial role in modifying the transition state energy of the reaction. These findings, along with other observations, cement the concept of polaritonic chemistry

Boosting Self-interaction of Molecular Vibrations under Ultra-strong Coupling Condition

In this letter, we investigated the modification of oscillator strength of an asymmetric stretching band of CS2 by strong coupling to an infrared cavity photon. This is achieved by placing liquid CS2 in a Fabry-Perot resonator and tune the cavity mode position to match with the molecular vibrational transition. Ultra-strong coupling improves the self-interaction of transition dipoles of asymmetric stretching band of CS2 that resulted in an increase of its own oscillator strength. We experimentally proved this by taking the area ratio of asymmetric stretching and combination band by selectively coupling the former one. A non-linear increase in the oscillator strength of the asymmetric stretching band is observed upon varying the coupling strength. This is explained by a quantum mechanical model that predicts quadratic behavior under ultra-strong coupling condition. These findings will set up a new paradigm for understanding chemical reaction modification by vacuum field coupling

Vibrational Ultra Strong Coupling of Water and Ice

Water is of vital importance for life and human activities on Earth—it exhibits unique properties due to its interlinked and multipoint hydrogen bonding network. Here, we experimentally show that water can undergo vibrational ultra strong coupling (V-USC) in both the liquid and solid forms when the OH stretching mode of water or ice is resonantly coupled with an optical mode of an infrared Fabry−Pérot cavity. The light-coupled H2O under V-USC reveals the largest Rabi splitting ever reported, reaching 22% and 26% of the vibrational energy for water and ice, respectively. We confirm that the extraordinarily large Rabi splitting stems from the densely packed minuscule molecular structures, large vibrational energies, and broad and intense absorptions due to intermolecular hydrogen bonding. These new findings offer a brand-new platform in polaritonic chemistry for controlling the properties of water with an ultra strong light-matter interaction

Enhanced Charge Transport in 2D materials through Polaritonic States

Here, we observed enhancement of charge transport in 2D materials by light-matter strong coupling. Charge transport mobility is enhanced by 50 times under ON resonance condition. A clear correlation in the effective mass of the polaritonic state and Schottky barrier height may be indicating a coherent nature of light-matter interaction.<br /

Cavity Catalysis: Modifying Linear Free-energy Relationship under Cooperative Vibrational Strong Coupling

Recent understanding of light-matter strong coupling brought a new niche in molecular-level control of chemical reactions. Vibrational strong coupling is unique in this category that overcomes the issue associated with coherent chemistry. Here, a vibrational transition is coupled to a standing wave of electromagnetic field, result in strong interaction, generating vibro-polaritonic states. This process reshuffles the entire energy-reaction coordinate. The chemical reaction rate can be boosted, stirred, or decelerated with this unconventional tool. Here, we used the idea of cooperative vibrational strong coupling of solute and solvent molecules to enhance the chemical reaction rate. This process is called cavity catalysis. Different derivatives of p-nitrophenyl benzoate (solute) and isopropyl acetate (solvent) are cooperatively coupled to an infrared Fabry-Perot cavity. The apparent reaction rates are increased by more than six times at the ON resonance condition, and the rate enhancement follows the lineshape of the vibrational envelope. Very interestingly, strong coupled system doesn\u27t follow a linear free-energy relationship. The nonlinear rate enhancement can be due to the reshuffling of energy distribution between the substituents and the reaction center. Thermodynamic parameters suggest an entropy-driven process for the coupled molecules. The free energy of activation decreased by 2-5 kJ/mol, suggesting a clear role of vibrational strong coupling in catalyzing the reaction. Here, the enthalpy of the system compensates for the entropy by preserving the isokinetic relationship. These findings will help further understanding of chemical reaction control in polariton chemistry