City University of Hong Kong
Department of Applied Physics and Material Science
AP 4178
Nanostructure and Nanotechnology
Lab Report of
Lab 1. Colloidal synthesis of gold nanoparticles
Date of Exp.: 14/10/2015
Liu Tsz Kwan
Objective
When we complete this laboratory, we are able to:
1. Applicate the concept of light scattering on particles in colloid suspension.
2. Differentiate the difference between reflection and absorption of UV.
3. Applicate the concept of reduction and oxidation we had learnt.
4. Compare effect of the color change and wavelength absorption on the different time and density of stock solution of the gold salt (HAuCl4).
Introduction
In this experiment we are going to mix the citrate stock solution (trisodium citrate, Na3C6H5O7H2O) with the stock solution of gold salt (HAuCl4). With two different amount of citrate stock solution add in and heated up into around 100 degree Celsius there will be color change (Figure 1). And we will also add the mixed solution into a small container and add in different amount of water by the pipet (Figure 2), in order to provide different density of the solution. Then put the solution into the Perkin Elmer Lambda 2 machine (Figure 3) to find out the absorption and reflection of the UV of the solutions. Also, we will heated up the solution in a longer period of time and find out the difference in the result between the solutions.
Figure 1. Color change Figure 2. Pipet Figure 3. Perkin Elmer Lambda
of the solutions 2 machine
In this experiment we need to do some safety precaution too, we need to wear gloves to do the experiment and we can take off the gloves when we put the small container in the Perkin Elmer Lambda 2 machine.
Materials used in the experiment:
· Glass cylinder
· 2 flask
· Magnetic stir bar
· Heater
· Stock solution of the gold salt (HAuCl4)
· Water
· Citrate stock solution (trisodium citrate, Na3C6H5O7H2O)
· Pipet
· 4 container
· Perkin Elmer Lambda 2
Theory
In this experiment the stock solution of gold salt (HAuCl4) are mixed with the citrate stock solution (trisodium citrate, Na3C6H5O7H2O), a reducing agent. So that the gold ions will be reduced to neutral gold particles. In the heating process the mixture of the solution was stirred vigorously, in order to make sure the gold particles in precipitate forms will be in similar size and will not stick together, also the heating process is to enhance the solutions’ stability.
Almost any types of amalgamation of single material can form a mixture of particles called Colloid. The mixtures of particles are smaller than the bare eye discrete through alternative substance.
Also Colloids will show the Tyndall effect, which is an effect of the tiny particles reflect the light in some kind of. This effect happens in a colloid since the small particles was scattered by the beam of light.
Procedure
· 1) Add 20 mL of 1.0 mM HAuCl4 to a 50 mL Erlenmeyer fl...
