Optical sequencing of single synthetic polymers.

Microscopic sequences of synthetic polymers play crucial roles in the polymer properties, but are generally unknown and inaccessible to traditional measurements. Here we report real-time optical sequencing of single synthetic copolymer chains under living polymerization conditions. We achieve this by carrying out multi-colour imaging of polymer growth by single catalysts at single-monomer resolution using CREATS (coupled reaction approach toward super-resolution imaging).

Tuning Single-Polymer Growth via Hydrogen Bonding in Conformational Entanglements.

Synthetic polymers have widespread applications in daily life and advanced materials applications. Making polymers efficiently and controllably is highly desired, for which modulating intramolecular and intermolecular interactions have been an effective approach. Recent real-time single-polymer growth studies uncovered nonequilibrium conformational entanglements that form stochastically under living polymerization conditions and which appear to plausibly play key roles in controlling the polymerization kinetics and dispersion.

Near-field thermal imaging of optically excited gold nanostructures: scaling principles for collective heating with heat dissipation into the surrounding medium.

In this paper, we introduce a new optical temperature and thermal imaging technique combining near-field microscopy and Er photoluminescence thermometry. The tip aperture of 120 nm limits the spatial resolution of near-field thermal imaging. We use the technique with two different approaches towards local temperature measurement and thermal imaging.

Targeted Nanoparticle Thermometry: A Method to Measure Local Temperature at the Nanoscale Point Where Water Vapor Nucleation Occurs.

An optical nanothermometer technique based on laser trapping, moving and targeted attaching an erbium oxide nanoparticle cluster is developed to measure the local temperature. The authors apply this new nanoscale temperature measuring technique (limited by the size of the nanoparticles) to measure the temperature of vapor nucleation in water. Vapor nucleation is observed after superheating water above the boiling point for degassed and nondegassed water.

Effect of Ions and Ionic Strength on Surface Plasmon Absorption of Single Gold Nanowires.

The local temperature change from a single optically excited gold nanowire, lithographically prepared on Al0.94Ga0.06N embedded with Er(3+) ions, is measured in air, pure water, and various concentrations of aqueous solutions of ionic solutes of NaCl, Na2SO4, and MgSO4.

Comparison of vapor formation of water at the solid/water interface to colloidal solutions using optically excited gold nanostructures.

The phase transformation properties of liquid water to vapor is characterized by optical excitation of the lithographically fabricated single gold nanowrenches and contrasted to the phase transformation properties of gold nanoparticles located and optically excited in a bulk solution system [two and three dimensions]. The 532 nm continuous wave excitation of a single gold nanowrench results in superheating of the water to the spinodal decomposition temperature of 580 ± 20 K with bubble formation below the spinodal decomposition temperature being a rare event. Between the spinodal decomposition temperature and the boiling point liquid water is trapped into a metastable state because a barrier to vapor nucleation exists that must be overcome before the thermodynamically stable state is realized.

Ultrasensitive molecular detection using thermal conductance of a hydrophobic gold-water interface.

The thermal conductance from a hydrophobic gold aqueous interface is measured with increasing solute concentration. A small amount of aqueous solute molecules (1 solute molecule in 550 water molecules) dramatically increases the heat dissipation into the surrounding liquid. This result is consistent with a thermal conductance that is limited by an interface interaction where minority aqueous components significantly alter the surface properties and heat transport through the interface.