Nanocrystalline particulate films

The experimental set-up used in the generation and in situ monitoring of semiconductor particulate films is identical to that used for nanosized, metallic, particulate films. Evolution of a nanocrystalline particulate film, illustrated by the formation of sulfide semiconductor particulate films (Fig. 110), has been discussed in terms of the following steps [639] ... 

Nanocrystalline particulate films, which exhibit pronounced quantum size effects in three dimensions, are of great interest due to applications in solar cell (108-112) and sensor (57, 113-115) applications. They exhibit novel properties due to not only the SQE manifested by individual nanoparticles but also the total surface area. Unlike MBE and MOCVD methods used to prepare quantum well electrodes, these electrodes can be prepared by conventional chemical routes described in Section 9.5.2.2. For example, II-VI semiconductor particulate films were prepared by using low concentrations of precursors and by controlling the temperature of the deposition bath. Nodes demonstrated the SQE for CdSe thin films deposited by an electroless method (98). The blue shift in the spectra of CdSe films has been demonstrated to be a function of bath temperature. As described in Section 9.5.2.1, electrodeposition of semiconductors in non-aqueous solvents leads to the formation of size-quantized semiconductor particles. On a single-crystal substrate, electrodeposition methods result in epitaxial growth (116, 117), and danonstrate quantum well properties. 

Kalyanasundaram K., Gratzel M. Applications of functionalized transition metal con5)lexes in photonic and optoelectronic devices. Coord. Chem. Rev. 1998 77 347-414 Kamat P.V. Photoelectrochemistry in particulate systems. 3. Phototransformations in the colloidal TiOa-thiocyanate system. Langmuir 1985 1 608-611 Kamat P.V., Bedja I., Hotchandani S., Patterson L.K. Photosensitization of nanocrystalline semiconductor films. Modulation of electron transfer between excited ruthenium complex and SnOa nanocrystalUne with an externally applied bias. J. Phys. Chem. 1996 100 4900-4908 Kamat P.V., Vinodgopal K. Environmental photochemistry with semiconductor nanoparticles. Mol. Supramol. Photochem. 1998 2 307-350... 

Nanodiamonds indicate synthetic diamond materials that have sizes or feature sizes (e.g., grain sizes) between 1 and lOOnm, generally including two forms particulate and thin film. Because the nanodiamond thin film is actually composed of nanosized columnar crystals or grains, the material is also known as nanocrystalline diamond. Due to its close relationship and similarity to nanodiamonds, nanostructured diamondlike carbon has also attracted considerable attention. In the following sections, these carbon nanostructures are discussed separately. 

Figure 5.4 SEM images of (a) particulate nanodiamond (PND) and (b) nanodiamond thin film or nanocrystalline diamond (NCD), (c) AFM image of NCD.

DNase, a well characterized and biologically specific enzyme with therapeutic value in the treatment of cystic fibrosis, was chosen as a model agent for studying the effects on an enzymatic bio/molecule of surface immobilization on nanocrystalline ceramic particulates. As the data show, and consistent with previous observations, DNase exhibits a marked retention of biological activity when surface immobilized on the solid phase of a colloid comprised of polyhydroxyl oligomeric films investing degradable calcium-phosphate nanoparticles. 

---