Particles cadmium selenide

Let us add here that the fabrication of polycrystalline semiconductive films with enhanced photoresponse and increased resistance to electrochemical corrosion has been attempted by introducing semiconductor particles of colloidal dimensions to bulk deposited films, following the well-developed practice of producing composite metal and alloy deposits with improved thermal, mechanical, or anti-corrosion properties. Eor instance, it has been reported that colloidal cadmium sulfide [105] or mercuric sulfide [106] inclusions significanfly improve photoactivity and corrosion resistance of electrodeposited cadmium selenide. 

Fine powdered cadmium reacts violently with selenium when it is heated. Nevertheless, the reaction is less violent than that of zinc with selenium. Therefore, one has to be careful when preparing cadmium selenide. The particle size of both reagents is a crucial safety factor regarding this reaction. 

Nickel and selenium interact with incandescence on gentle heating [1], as do also sodium and potassium, the latter mildly explosively [2], Uranium [3] and zinc [4] also incandesce when their mixtures with selenium are heated, and platinum sponge incandesces vividly [5], The particle size of cadmium and selenium must be below a critical size to prevent explosions during synthesis of cadmium selenide by heating the elements together. Similar considerations also apply to interaction of cadmium or zinc with sulfur, selenium or tellurium [6], Interaction of powdered tin and selenium at 350° C is extremely exothermic [7],... 

Fig. 17 Cadmium selenide QDs, dissolved in toluene, fluorescing brightly in the presence of a ultraviolet lamp, in three noticeably different colors (blue 481 nm, green 520 nm, and orange 612 nm). The blue QDs have the smallest particle size, the green dots are slightly larger, and the orange dots are the largest. (Adapted from http //www. amazingrust.com/ experiments/current proj ects / Misc.html)...

Emrick and Coughlin et al. reported on the synthesis of cadmium selenide-polymer composites. A vinylbenzyl-derivatized phosphine oxide was ph-ysisorbed onto cadmium selenide particles. Subsequent reaction with RUCI2 (PCy3)2(CHPh) or RuCl2(NHC)(PCy3)(CHPh) (NHC= 1,3-dimesityhmidazol-2-ylidene) followed by addition of cyclooctene, 7-oxanorborn-5-ene-2,3-dicarboxylic anhydride, dicyclopentadiene or N-methyl-7-oxanorborn-5-... 

Gobet and Matijevic (17) produced monodisperse submicrometer-size particles of cadmium selenide (CdSe) and lead selenide (PbSe) by reversible release of selenide ions from selenourea in solutions of the corresponding metal salts. The equilibrium between selenourea and selenide ions is written as follows ... 

The analogous capping of cadmium selenide particles by organo(silyl)-selenides in reversed micelles will be discussed in Sect. 4.4. 

Metals. Nickel, sodium, potassium, uranium, zinc, and platinum sponge interact with selenium with incandescence when gently heated.3-7 The particle size of cadmium and selenium must be below a critical size to prevent explosions when making cadmium selenide this also applies to zinc.8... 

If the nanodispersed species have sizes of the order of 10 nm, diagnostic agents encapsulated in such nanoparticles could potentially cross into human cells. For example, 10 nm diameter, silica-coated, cadmium selenide crystals have been able to transfer into vesicles and be transported by them [901], These protein-sized particles fluoresce for long periods of time making them potentially useful for diagnostic labelling. 

Carter A, Bouldin CE, Keiimer KM, Bell MI, Woicik JC, Majetich SA (1997) Surface structure of cadmium selenide nanociystallites. Phys Rev B 55 13822-13828 Caruso F (2001) Nanoengineering of Particle Stufaces. Adv Mater 13 11-22... 

HfSkaff and Rmrick bound RAFT agent functionality to cadmium selenide nanoparticles by a ligand exchange process and grew various narrow MWD polymers (PS, PMA, PBA, PS-c o-MA, PS-co-AA, PS-co-IP, S-block-PMA, PS-ii/oc -PBA) from these particles. 

Although the possible formation mechanism of nanocrystalline cadmium selenide is not very clear in ethylenediamine (en) by y-iiradiation, the formation process of CdSe particles in en is similar to that of CdS in water. So drawing an analogy with the formation mechanism of sulfides in aqueous system, a possible process of reactions is speculated ... 

The layer-by-layer structure of dithiol SAM and CdS monolayer was confirmed with X-ray photoelectron spectroscopy, Fourier transform infrared reflection-absorption spectroscopy, and inductively coupled plasma mass spectroscopy at each step of composite-film preparation. Photocurrent measurements revealed that the mono-layers of CdS nanoparticles were immobilized without mutual aggregation of particles [36]. Cadmium selenide nanoparticles were prepared electrochemically on gold substrates modified with alkanethio-lated -cyclodextrin SAMs [37]. 

Botti and Marques addressed this problem for two experimentally synthesized cadmium selenide nanoparticles (CdSe)33 and (CdSe)34. For these clusters, the X-ray analysis showed a coordination number between 3 and 4 for the selenium atoms, which gave rise to the assumption of a cage-like structure. These cage structures are significantly different from structures that are derived from the wurtzite crystal structure, where the resulting particles are rather compact. So far, there has not been any experimental proof of the existence of such CdSe cages. 

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