Photochemical Dynamics of Fullerene Nanoparticles
When the sizes of particles or layers of metals and semiconductors become as small as the nanometer-scale, they show quite attractive properties that are different from bulk materials [1 ]. The quantum-size effect is one of the important properties of nan
- PDF / 1,781,398 Bytes
- 12 Pages / 439 x 666 pts Page_size
- 91 Downloads / 248 Views
17.1
Introduction
When the sizes of particles or layers of metals and semiconductors become as small as the nanometer-scale, they show quite attractive properties that are different from bulk materials [1]. The quantum-size effect is one of the important properties of nanostructured materials. Nonlinear optical properties of these materials are also important in applications to photonic devices [2]. Furthermore, the wide surface area of fine particles enhances the efficiencies of solar cells utilizing dye-sensitized Ti0 2 [3]. Thus, fabrication of nanostructures is an important means of attaining novel properties and is studied extensively in the field of material science. As for organic materials, one can donate desired properties to molecules by molecular design and syntheses. Furthermore, nanostructured materials have been fabricated by several procedures. Fine crystals, mono- or multilayered membranes, dendrimers, and artificial proteins are examples of nanostructured materials of organic compounds. Among them, organic fine crystals are an important class of materials for nanotechnology, since their properties are expected to change depending on their size, while little has been known on their properties. Recently, systematic studies of the preparation methods of organic fine crystals have enabled us to clarify their properties [4]. Photoexcitation and relaxation properties seem to be important to elucidate their structure- and size-dependent properties. Changes in their electronic structures and chemical reactivities can be experimentally observed by using several fast laser techniques and so on. In the present chapter, we summarize the photophysical and photochemical properties of nanostructured materials, such as fine particles based on our recent research results. Although nanoparticles are interesting materials, little has been known about them. In particular, photodynamic properties of nanoparticles of fullerenes such as C 60 (Fig. 17.1) and its related compounds are mainly described, since fullerenes have attracted much attention in many fields of chemistry. The present review will give useful information on the possible application of nanostructured materials.
H. Masuhara et al. (eds.), Single Organic Nanoparticles © Springer-Verlag Berlin Heidelberg 2003
214
M. Fujitsuka and O. Ito
Fig. 17.1. C60 and C70 fullerenes
17.2
Photoexcitation of Organic Nanopartic1es
Organic fine crystals have been obtained in several ways. Details of the preparation methods will be described in the other sections. The methods can be classified into roughly two groups: Preparation processes in the vapor phase and liquid phase. The former process generates fine crystals from evaporated organic materials at low pressure and the latter process generates fine crystals as precipitates from solution. In general, the latter process, the reprecipitation method, can be applied to a wide variety of organic samples even if the sample is unstable under high temperature and/or low pressure conditions. Thus, the fine crystals obt
Data Loading...
