An innovative technique for analyzing nanoparticles made of cadmium telluride (CdTe) has been used by researchers from the Siberian Federal University and Kirensky Institute of Physics (Siberian Department of the Russian Academy of Sciences).
They used a strange attribute of this compound: depending on the magnetic field, there were variations in its interaction with light. The outcomes of the research have been reported in the Physics Letters A journal.
The magnetic characteristics of an environment govern the interaction of specific substances with electromagnetic radiation. Specifically, a vital role could be played by the magnetic circular dichroism effect. In the presence of this phenomenon, there is a difference in the absorption of light with distinctive circular polarizations if it travels along the direction of magnetization. The properties of the substance itself (in case of ferromagnetic materials) or the impact of an external magnetic field can be used to determine the magnetization.
Physicists from the Siberian Federal University have been developing structures from colloidal (suspended in a medium; here water) quantum dots.
Due to the tiny size of these objects (quantum dots are about three nanometers in diameter) the final structures are also quite small. After the experiments are over, and structures are formed, they need to be studied - for instance, using electron microscopy or light spectroscopy. However, in the case of electron microscopy first of all the object should be deposited on a surface, which may cause the structure to change.
Alexey Tsipotan, Co-Author
While looking for the new technique, the researchers proposed the use of the magneto-optic effect to analyze the structures without carrying out any additional modifications. The colloidal nanoparticles in question appeared to possess the magnetic circular dichroism effect. Hence, methods based on this could be applied for the analysis of the developed structures. Since cadmium telluride particles do not have intrinsic magnetism, this effect can be seen only under the impact of an external magnetic field.
The potential range of use of colloidal quantum dots is extremely wide. Most notably, they are excellent luminophores - their quantum yield of luminescence is on the same level as in dyes, but they are more photostable, i.e. they don’t fade away under the influence of sunlight. Due to this property they may be used as light-emitting elements of optical diodes. Also, they may be used in solar cells for more efficient sunlight transformation. Another area of their potential application is biology where quantum dots may be used as markers. Moreover, Samsung has recently launched a TV set in which quantum dots are added to light-emitting diodes.
Alexey Tsipotan, Co-Author