Circular dichroism (CD) spectroscopy is a powerful optical technique for the study of chiral materials and molecules. It gives access to an enantioselective signal based on differential absorption right left circularly polarized light, usually obtained through polarization analysis light transmitted sample interest. CD routinely used determine secondary structure proteins their conformational state. However, signals are weak, limiting use this ensembles many Here, we experimentally realize...

We simultaneously measured the absorption and emission of single conjugated polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) molecules in a poly(methyl methacrylate) (PMMA) matrix using near-critical xenon to enhance photothermal contrast for direct measurements. directly number monomers quantum yield molecules. Simultaneous measurements provided new insight into photophysics polymers under optical excitation: quenching larger is more efficient than smaller ones....

Magnetic nanomaterials record information as fast picoseconds in computer memories but retain it for millions of years ancient rocks. This exceedingly broad range times is covered by hopping over a potential energy barrier through temperature, ultrafast optical excitation, mechanical stress, or microwaves. As switching depends on nanoparticle size, shape, orientation, and material properties, only single-nanoparticle studies can eliminate the ensemble heterogeneity. Here, we push sensitivity...

Plasmonic waveguides are key elements in nanophotonic devices, serving as optical interconnects between nanoscale light sources and detectors. Multimode operation plasmonic two-wire transmission lines promises important degrees of freedom for near-field manipulation information encoding. However, highly confined plasmon propagation along gold nanostructures is typically limited to the near-infrared region due ohmic losses, excluding all visible quantum emitters from circuitry. We report on...

The local interaction of charges and light in organic solids is the basis distinct fundamental effects. We here observe, at single-molecule scale, how a focused laser beam can locally shift by hundreds times their natural line width and, persistent way, transition frequency chromophores cooled liquid helium temperature different host matrices. Supported quantum chemistry calculations, results be interpreted as effects photoionization cascade, leading to stable electric field, which...

Temperature dependent measurements of the rotational diffusion single dye molecules in polymer poly(methyl acrylate) (PMA) are presented and compared to shear viscosity data numerical simulations process. It is found that molecule very accurately follows Debye-Stokes–Einstein predictions for without any additional parameter. We employ a simple model dynamic changes speed molecule. This heterogeneity based on Gaussian distribution activation energies VFTH (Vogel-Fulcher-Tammann-Hesse) type...

Circular dichroism (CD) is the property of chiral nanoobjects to absorb circularly polarized light either handedness different extents. Photothermal microscopy enables detection CD signals with high sensitivity and provides a direct absorptive response samples under study. To achieve measurements at single-particle level, one must reduce such artifacts as leakage linear (LD) residual intensity modulation. We have simulated our setup simple model, which allows us tune modulation parameters...

In the last three decades, cryogenic single-molecule fluorescence spectroscopy has provided average-free understanding of photophysics and fundamental interactions at molecular scales. Furthermore, they propose original pathways applications in treatment storage quantum information. The ultranarrow lifetime-limited zero-phonon line acts as an excellent sensor to local perturbations caused either by intrinsic dynamical degrees freedom, or external perturbations, such those electric fields,...

Chemically synthesized metal nanoparticles with morphological chiral features are known to exhibit strong circular dichroism. However, we still lack understanding of the correlation between and chiroptical plasmonic nanoparticles. To shed light on that question, single nanoparticle experiments required. We performed photothermal dichroism measurements achiral gold correlated response 3D morphology same retrieved by electron tomography. In contrast an ensemble measurement, show individual...

Magnetic imaging is a versatile tool in biological and condensed-matter physics. Existing magnetic techniques either require demanding experimental conditions which restrict the range of their applications or lack spatial resolution required for single-particle measurements. Here, we combine photothermal (PT) microscopy with circular dichroism (MCD) to develop technique using visible light. Unlike most techniques, (PT MCD) works particularly well single nanoparticles immersed liquids. As...

Synthetic antiferromagnetic nanoplatelets (NPs) with a large perpendicular magnetic anisotropy (SAF-PMA NPs) have potential in future local mechanical torque-transfer applications for e.g., biomedicine. However, the mechanisms of magnetization switching these structures at nanoscale are not well understood. Here, we used simple and relatively fast single-particle optical technique that goes beyond diffraction limit to measure photothermal circular dichroism (PT MCD). This allows us study as...

Photothermal (PT) microscopy has shown strong promise in imaging single absorbing nano-objects soft matter and biological systems. PT at ambient conditions usually requires a high laser power for sensitive detection, which prevents application to light-sensitive nanoparticles. In previous study of gold nanoparticles, we showed that the photothermal signal can be enhanced more than 1000-fold near-critical xenon compared glycerol, typical medium detection. this report, show carbon dioxide...

Optoplasmonic bio-detection assays commonly probe the response of plasmonic nanostructures to changes in their dielectric environment. The accurate detection nanoscale entities such as virus particles, micelles and proteins requires optimization multiple experimental parameters. Performing directly via analyte recognition is often not desirable or feasible, especially if exhibit limited numbers binding sites irreversible. Here we introduce photothermal spectro-microscopy a benchmarking tool...

Time-resolved spectroscopy of plasmonic nanoparticles is a vital technique for probing their ultrafast electron dynamics and subsequent acoustic photothermal properties. Traditionally, these experiments are performed with spectrally broad probe beams on the ensemble level to achieve high signal amplitudes. However, relaxation highly dependent size, shape, crystallinity. As such, inherent heterogeneity most nanoparticle samples can complicate efforts build microscopic models solely basis...

Chiral nanoparticles are those nanostructures whose mirror image cannot be superimposed onto each other. Enantiomers of a chiral nanoparticle interact differently with left- and right-circularly polarized light. Circular dichroism (CD) is the differential absorption birefringence (CB) or optical rotatory dispersion (ORD) rotation polarization direction linearly light through medium. CD CB respectively related to imaginary real part dielectric function. Standard detection single based on...

Polymers are very heterogeneous close to glass transition temperature (T g ) and a complex dynamics with non-exponential relaxation is observed by bulk techniques as well single molecule (SM) techniques.We have performed measurements of rotational diffusion perylene dimide (PDI) dye molecules in poly (methyl acrylate) (PMA) (vinyl acetate) (PVAc) their T .We found that the temporally heterogeneity changes change temperature.SM results compared from dielectric shear viscosity data.Average...

Abstract Detection of single molecules or particles avoids ensemble averaging and thus is able to provide a very local heterogeneous information which not available from an measurement. Single can be detected based on their three characteristic optical properties, absorption, scattering fluorescence/photoluminescence, in addition label-free detection. This short review focuses our group’s research towards understanding imaging the above kinds signals particles.