Effects of Intensity and Energy of CW UV Light on the Growth of Gold Nanorods

Abstract

Growth of gold nanorods (AuNRs) by photochemical reduction of HAuCl4 in a micelle solution of hexadecyltrimethylammonium bromide (CTAB) and tetraoctylammonium bromide (TOAB) is studied. The effects of 300 and 254 nm UV light sources and their photon flux on the anisotropic growth of gold nanoparticles are investigated by controlling duration of irradiation and the number of lamps within a photochemical reactor. The resulting AuNRs were characterized by absorption spectroscopy, FTIR, and TEM. Experimental results indicate that a higher density of longer colloidal AuNRs form by increasing the number of incident photons (lamps) at 300 nm while the 254 nm lights produce a lower yield of shorter AuNRs. The yield of AuNRs also depends on the duration of irradiation which was found to be 6.00 h for 300 nm and 5.00 h for 254 nm radiation. Acetone is found to play a major role in the synthesis of AuNRs. Two mechanisms are proposed for the synthesis of Au nanoparticles in the presence and absence of acetone. Irradiation of samples for an excess time produces a lower concentration of AuNRs and a higher yield of spherical particles. This effect is attributed to atom-by-atom dissolution of AuNRs into Au-spherical particles.

Determination of Aspect-Ratio Distribution in Gold Nanowires Using Absorption Spectra and Transmission Electron Microscopy Techniques

“…In this paper, we will use the original shape factors of Gans theory, but with the dielectric constant of the medium, m ε , as a variable. Studies by Miranda and Ahmadi (Miranda & Ahmadi 2005) and Gulati et al (Gulati et al 2006) indicate that the local dielectric properties have a strong influence on the optical absorption characteristics. The presence of a surfactant around the nanowires is one of the reasons why the dielectric constant can locally be different.…”

“…This has great advantages for the use of nanowires in surface-enhanced Raman spectroscopy Sztainbuch, 2006;Suzuki et al , 2005, medical imaging, disease treatment, and other applications such as highly sensitive sensors (Agarwal et al 2007;Gibbons et al 2006;Yu & Irudayaraj 2007;Chen et al 2007). For this reason, the fabrication processes for nanowires and the characterization of their optical properties are of great interest in current research Gulati et al 2006;Miranda & Ahmadi 2005;Zweifel & Wei 2005;Hu et al 2003;Sönnichsen et al 2002). It would be useful to have a quick and easy way to accurately determine the size distribution of nanoparticles in solution in order to analyze nanowire synthesis processes or characterize samples for applications.…”

Konjac Biomolecules Assisted–Rod/Spherical Shaped Lead Nano Powder Synthesized by Electrolytic Process and Its Characterization Studies

“…From earlier reports, gold nanorods have been intensively affected by the wavelength of UV light source and their photon flux [8]; rod like gold particles have been prepared by UV irradiation; Metals have strongly absorb light in the visible region due to surface plasma resonance [9]; the number of surface amino group of dendrimers have a key factor to control the particles with UV irradiation method [10]; stabilization of metal nanoparticles by protein is possible one [11]; proteins can bind to nanoparticles either through free amine groups or cysteine residues in the proteins [12]; and via the electrostatic attraction of negatively charged carboxylate groups in enzymes present in the cell wall of bacteria [13].…”

Investigation of pH Effect on Gold Nanorod Synthesis

“…1,2 To obtain GNRs with desired size-and shapedependent optical properties 3 and biocompatibility, a wealth amount of methods have been developed for the shape control of GNRs, 2,4 such as chemical synthesis using a template, 5 electrochemistry or photochemistry based methods, 6,7,8 seed-mediated growth, 9,10,11 reshaping by overgrowth or oxidation. 12,13,14,15 Among them, the seedmediated growth method is a robust and widely used method, which was introduced initially by Catherine J. Murphy 9 and later improved by El-Sayed and coworkers.…”