Quantum dots, semiconducting

Pejova et al. [72] (2008) have obtained three-dimensional arrays of close-packed semiconducting AgBiS2 quantum dots with an average QD radius of 4.2 nm using sonochemical method which was twice as small as compared to the QD solid obtained without ultrasonic irradiation. 

Pejova B, Grozdanov I, Nesheva D, Petrova A (2008) Size-dependent properties of sono-chemically synthesized three-dimensional arrays of close-packed semiconducting AgBiS2 quantum dots. Chem Mater 20(7) 2551-2565... 

Amidation and esterification are also widely exploited. CNTs-amide bonds are found as part of linking agents employed to covalently attach nanoparticles, generally metals or semiconducting quantum dots (QDs), via ex situ synthesis. These linkers are frequently bifunctional, possessing an additional anchoring site that is bound to the nanoparticle side. For example, modified CdSe QDs have been attached via an amine-terminated amido linker (Fig. 3.18) [97], while Au nanoparticles are often attached through mercapto-terminated linkers [98],... 

Semiconducting nanocrystals, usually CdSe-ZnS crystals a few nanometers in diameter, called quantum dots, can be useful for in vivo imaging of biochemical dynamics but still suffer from three limitations.51 The most severe problem is that quantum dots blink at probability distributions that lead to loss of continuity in keeping track of individual molecules, limiting the ability to measure the dynamics and mechanisms of biophysical chemistry in vivo and ex vivo. Some significant fraction of fabricated quantum dots appear to be totally dark, reducing... 

These factors, in turn, are dependent on the diameter and helicity. It has been found that metallicity occurs whenever (2n + m) or (2 + 2m) is an integer multiple of three. Hence, the armchair nanotube is metallic. Metallicity can only be exactly reached in the armchair nanotube. The zigzag nanombes can be semimetallic or semiconducting with a narrow band gap that is approximately inversely proportional to the tube radius, typically between 0.5 -1.0 eV. As the diameter of the nanombe increases, the band gap tends to zero, as in graphene. It should be pointed out that, theoretically, if sufficiently short nanotubes electrons are predicted to be confined to a discrete set of energy levels along all three orthogonal directions. Such nanotubes could be classified as zero-dimensional quantum dots. 

This chapter will address issues concerned with the synthesis of quantum dots in quantity. Many issues remain ill-defined in this area including the simple problem of defining what will form a proper specification for nanodimensional materials such as quantum dots. A typical material may involve two types of solid-state compound and an apparently ever increasingly complex orgamc coat used to enhance the stability of the material and the solvents in which it can be dispersed/ processed. Again analogies with conventional semiconducting materials can be... 

A final interesting development is that of quantum-dot-loaded particles. Quantum dots [52] are themselves very small semiconducting colloids (1-lOnm) which fluoresce due to quantum confinement. They can be trapped within a polymer or silica [53] colloid. Since quantum dots photobleach much less than organic dyes, they can be used for experiments involving long-term observation. 

Metal chalcogenide aerogels prepared by condensation of metal chalcogenide nanoparticles (quantum dots) exhibit unique optical properties. What are these properties and how does the aerogel dimensionality determine the extent of quantum confinement You may wish to consult Chapter 16 on semiconducting nanoparticles in answering this question. 

Professor Wang, Dr Jia and Dr Li have written about the Electro-chemiluminesence of a set of particular Ruthenium (bipyridyl) complexes. Dr Viswanatha and Dr Pandey have described the study of semiconducting quantum dots using optical spectroscopy in both frequency and time domains. 

Electrochemical Synthesis of Quantum Dots and Semiconducting Nanocompounds... 

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