The light emission observed from small palladium particles during passage of electronic current

Light emission spectra were measured from separate Pd particles excited by the passage of electrical current through them. As the particle size decreases or input power increases the intensities of peaks increase more strongly in the high-energy part of the spectra than in the low-energy part. Moreover, new peaks can appear in the high-energy region. The color of an emission center changes from red to blue upon an increase in electric power fed into the Pd particle. This process is reversible and can be observed visually. On a further increase in feeding power, the Pd particle can be brought to a premolten state and can even melt. The integral intensity of light emission then increases dramatically, and the light emission spectrum changes and corresponds to thermal radiation. This latter process is irreversible

Electroluminescence spectra of porous silicon as a function of the applied voltage

The spectra of light emission from a separate emission center in porous silicon contained in "sandwich" structures were measured under the passage of electrical current as a function of applied voltage. The light intensity increases quicker in the short-wave part of the spectrum than in the long-wave part on increasing the voltage. Such a feature of the spectrum change has been observed earlier for island metal films

Magnetic sensitivity of a dispersion of aggregated ferromagnetic carbon nanotubes in liquid crystals

Using carbon nanotubes filled with alpha-Fe, we have shown that aggregated ferronematic colloids demonstrate reliable and very effective response to a weak (<5 mT) magnetic field. The magnetic field realigns the aggregates of the particles which results in a non-threshold reorientation of the LC nearby, leading to the optically observed director distortions. The distortion regions expand with the increase of the magnetic field and achieve maximum size of several micrometres, comparable with the size of the agglomerates. In the non-distorted regions the reorientation of the director begins at the magnetic field reaching the Freedericksz transition value. Taking into account the extreme sensitivity of aggregated ferronematics to magnetic field, the following experimental and theoretical studies of the individual response of the aggregated nanoparticles to magnetic field may became the topical task of the physics and applications of ferronematics