Biomedical subjects

Meindert A van Dijk

Publications and source records attributed to Meindert A van Dijk.

3 recordsLinked to original sources

PubMed2005

Detection of acoustic oscillations of single gold nanospheres by time-resolved interferometry.

We measure the transient absorption of single gold particles with a common-path interferometer. The prompt electronic part of the signal provides images for diameters as small as 10 nm. Mechanical vibrations of single particles appear on a longer time scale (period of 16 ps for 50 nm diameter). They reveal the full heterogeneity of the ensemble, and the intrinsic damping of the vibration. We also observe a lower-frequency mode involving shear. Ultrafast pump-probe spectroscopy of individual particles opens new insight into mechanical properties of nanometer-sized objects.

Journal Article↗

PubMed2005

Far-field optical microscopy of single metal nanoparticles.

Individual noble-metal particles, with sizes ranging from a few tenths to some hundreds of nanometers, can now be detected by far-field optics. Single-particle microscopy gives access to inhomogeneity, distributions, and fluctuations, which were previously hidden in ensemble experiments. Scattering methods rely on dark-field illumination, spectral signatures of the metal particles, or both. More advanced techniques provide high sensitivity and improved selectivity with respect to other scatterers by isolating metal-specific signals, for example the refractive index change due to heating of the environment by a pump beam or the time-resolved optical response of the particle to a short pump pulse. We review and compare linear and nonlinear methods in far-field optical microscopy that have reached the single-particle regime by means of scattered light, thermal effects, photoluminescence, or nonlinear frequency generation.

Journal Article↗

PubMed2005

Third-harmonic generation from single gold nanoparticles.

We report the first observation of third-harmonic signals from individual gold colloids down to 40 nm diameter. Excited with 1-ps pulses at 1500 nm, the colloids generate 500-nm light, close to the plasmon resonance. The third-harmonic intensity varies as the square of the colloid surface area. Although weak, the third-harmonic signals of gold labels as small as 15 nm in diameter are expected to be accessible with 100-fs pulses. They could be used in microscopy for single-biomolecule tracking.

Gold Colloid↗