Nanocrystals Essay

SURFACE MODIFICATIONS OF CuO NANOCRYSTALS USING TRIETHANOLAMINE AS A CAPPING AGENT USING NEW OXIDE SOURCE BY SOL-GEL TECHNIQUE

L. Sugia S. Dheivamalara* J. Jayaprakashb K. Ambigaic a, a* Department of physics, Government Arts College for women (Autonomous), Pudukkottai bDepartment of Physics, Annamalai University, Annamalai Nagar 608 002, India cDepartment of physics, Bharath College of Science and Management, Thanjavur

ABSTRACT

The uncapped and capped CuO nanocrystals were synthesized by sol–gel technique. Triethanolamine (TEA) used as a capping agent to control the size, morphology and optical properties of the CuO nanocrystals. The optical properties of Cu nanocrystals are cognizant of using Triethanolamine is a capping agent. The obtained

Commonly nanocrystals synthesis depends upon the temperature and stirring rate. We increased the temperature, resulting from the reducing of stirring rate. Therefore, in the present study, we chose the 80 °C as temperature. Triethanolamine (TEA) as capping agent to study their effects on the size and morphology of CuO nanocrystals. The present investigation occurring a new oxide source Coumarin used to prepare CuO nanocrystals. Coumarin (C9H6O2) is an aromatic compound (1, 2 benzopyrone or α-benzopyrone) acquires from natural products. It is one of the most active classes of compounds exhibiting a wide spectrum of biological activity. Molecular structure of a capping agent with the reacting group as shown in Table 1. Coumarin is important natural occurring and synthetic compounds which show several relevant applications. That’s we have been chosen to Coumarin as oxide

The fundamental absorption, which corresponds to electron excitation from the valence band to the conduction band, can be used to determine the nature and value of the optical band gap [21]. As seen, a narrow and weak emission band around 420 nm and 495 nm, using an excitation wavelength of 250 nm was recorded for the uncapped and TEA capped CuO nanocrystals. Meanwhile, a comparison between uncapped and TEA capped CuO nanocrystals clearly revealed that there are two distinct emission bands in their Photoluminescence spectra. The uncapped CuO nanocrystals were sharp, narrow and symmetric located at about 492 nm and 396 nm. In addition, TEA capped CuO nanocrystals were sharp, narrow and symmetric located at about 495 nm and 420 nm respectively. A dominant sharp emission peaks at 492 nm and 495 nm of the uncapped and TEA capped CuO nanocrystals were observed in violet to blue region supports the blue-shift behavior of the peak position, in comparison with bulk CuO. This observed blue-shift behavior is attributed to the enhanced quantum confinement effect due to decrease in the dimensions of the nanostructures. The uncapped and TEA capped CuO nanocrystals luminescence blue bands at 491 and 495 nm are caused by transition vacancy of oxygen and interstitial oxygen. However, the uncapped and TEA capped CuO nanocrystals photoluminescence