Biomedical subjects

A J Hallock

Publications and source records attributed to A J Hallock.

3 recordsLinked to original sources

PubMed2005

Optical forces between metallic particles.

We calculate the optical attractive forces that occur between 30-nm Au or Ag nanocrystals when irradiated at visible wavelengths. These forces show resonances at dipolar plasmon wavelengths, similar to resonances in the near-field electromagnetic intensities. At MW/cm2 intensities, optical forces can be stronger than van der Waals forces and could be used to organize metallic particles. We also suggest that photonucleation of organic crystals from supersaturated liquid solutions may be caused by optical forces.

Journal Article↗

PubMed2005

Electrochemical ostwald ripening of colloidal ag particles on conductive substrates.

Thermally evaporated silver nanoparticles on conducting substrates spontaneously evolve in size when immersed in pure water. The process was studied using scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and optical absorption spectroscopy. The particles are proposed to reform through an electrochemical Ostwald ripening mechanism driven by the size dependence of the work function and standard electrode potential. We also discuss prior literature experiments where this process appears to occur. Our results show the sensitivity of the electrochemical properties of metallic nanoparticles at relatively large sizes (approximately 50 nm).

Journal Article↗

PubMed2003

Use of broadband, continuous-wave diode lasers in cavity ring-down spectroscopy for liquid samples.

Cavity ring-down spectroscopy (CRDS) is an extremely sensitive absorption technique that has been applied primarily to gas samples, which are characterized by having narrow absorption features. Recently, CRDS has also been applied to liquid samples, which have broad absorption features. The use of small inexpensive diode lasers as light sources for liquid samples is demonstrated. The low cost coupled with the ease and technical straightforwardness of application gives this technique wide appeal.

Acetonitriles↗