Under C <sub> 60 </ Sub> Preparation Of Mixed Langmuir-blodgett Films At Room Temperature And Fluorescence Characteristics

Since the discovery in 1985, the C₆₀ molecule attract much attention because its ideal symmetry, unique physical and chemical properties and potential applications. In 1990, Kratschmer and Huffman discovered an efficient preparation method for high pour C₆₀, the properties of C₆₀ have been extensively studied by scientists.C₆₀ is of great interest because of the numerous potential applications in physics and chemistry. Among the properties of C₆₀, photoluminescence (PL) which has potential application in areas such as optics, electrics, materials science and biomedicine et al is of great importance. It is significant to investigate the emission mechanism to achieve high-quality PL of C₆₀, especially at room temperature. In the last years many studies have been focused on the optical characterization of both C₆₀ molecules and solid fullerite. In particular, PL measurements have been performed on dilute molecular solutions, films, polycrystalline powders and single crystals. The PL spectra of C₆₀ film, which have been fabricated using many methods, such as powder sublimation, epitaxial growth, cast film and so on, have been measured on varies substrate. Many groups found that the PL spectra of C₆₀ film depending on the temperature greatly and only under low temperature(≤10 K) can we get rich PL emission.The Langmuir-Blodgett (LB) technique is one of the most powerful tools to form organic ultrathin films in molecular thickness. So it is an attractive idea to form C₆₀ LB films, and to measure their PL. Usually film-forming molecules should be amphiphilic. C₆₀ molecule is not a typical amphiphilic molecule. When C₆₀ was spread on the air-water surface, the molecules of C₆₀ always aggregated. So it is very difficult to fabricate homogeneous pure C₆₀ LB film. And as a result very few works on PL of C₆₀ LB films have been carried out. The reports of the PL spectra of C₆₀ LB films are also very few.In this paper, we not only fabricate the C₆₀ LB film and C₆₀/SA mixed LB film but also measure the PL signals and photographs observations on C₆₀ and SA mixed LB films deposited on silicon substrate. All experiments are carried out at room temperature. In order to obtain the LB films of C₆₀ with good quality people mixed other molecules, such as stearic acid or arachidic acid, with C₆₀ molecules. These methods do work, but the improvements are of different level. We selected two methods of them to prepare the C₆₀ LB film in the samecondition, and then compared the films come from the two methods. PL of the LB films wascharacterized using an argon-ion laser (514.5nm) as an excitation source. We obtained two PL bands centered at 731nm and 806nm respectively, which are more intense than that of other kinds of films. It is supposed that the particular ordered net-like construction of the LB film plays a crucial role in the enhancement of the photoluminescence. The 731nm PL band is related with the aggregation state of the particles and the 806nm PL band is referred as the intrinsic PL spectrum of the C₆₀.At last I will show you an interesting phenomena we observed in researching the ultrasonic, one of the variables of the process to fabricate the C₆₀ LB film, which take me very long time. It is the three-dimensional self-organization of C₆₀ hollow decagon nanoprisms. The reason why this happened has not very clear. The conclusion I can draw now is that the ultrasonic can influenced the surface configuration of the C₆₀ LB film greatly.The conclusion above not only open a door way for further systematic studies of fluorescence of C₆₀ LB film, but also provide a novel application potential of fullerne LB film at room temperature in photosensitive and luminescent material.