lab 3 light & nanotechnology
DESCRIPTION
September 23, 2011. Lab 3 Light & nanotechnology. Background. Materials at the nanoscale. Background. What is nanoscience? What is considered nanoscale? What is the significance?. Fullerene (C 60 , DTRANSCRIPT
September 23, 2011
Background
Background
What is nanoscience? What is considered nanoscale? What is the significance?
Fullerene (C60, D<5nm)
Nobel Prize in Chemistry 1996
Harold Kroto, Robert Curl & Richard Smalley (Rice University)
Graphene
Nobel Prize in Physics 2010
Andre Geim & Konstantin Novoselov (University of Manchester)
Carbon Nanotubes (D ~ 4 nm)
Quantum Dots (5 to 50 nm)
Gold Nanoparticles
HeLa cells with fluorescent gold nanoparticles
(Dr. Mengxiao Yu and Dr. Jie Zheng – UT Dallas).
Background
Properties of Light
Light is a wave (Electromagnetic (EM) radiation)
Waves have 3 features Wavelength (λ) Amplitude Frequency (ν)
EM radiation = continuous spectrum of all wavelengths (no gaps).
Electromagnetic Spectrum
Equations of Light
c = λν, c is the speed of light (m/s), λ is the wavelength (m) , ν is the frequency (s-1)
∆E = hν h is Planck’s constant (J s) ν is the frequency (s-1)
∆E = (hc)/λ
When light hits an object… Different wavelengths can be…
Absorbed Transmitted (allowed to pass through) Reflected
…depending on the wavelengths of light, object’s chemical composition, and its size.
Color Wheel
Object absorbs orange = blue color observed.
No light absorbed = all are reflected or transmitted (white light).
All wavelengths are absorbed = black color observed.
How to separate light
Prism Diffraction
Figure 5: Diffraction of light (pg 25) w(sinθn) = nλ tan(θn) = yn/L
Purpose
Measure the width of a single hair using a laser pointer and diffraction.
Synthesize Ag NPs, and investigate how color is related to particle size.
Materials
Laser pointer Measuring tape Scotch tape Hair Stock solutions (Sodium citrate, silver
nitrate, hydrogen peroxide, potassium bromide, sodium borohydride)
Large test tubes Stoppers or parafilm to seal test tubes Spectrophotometer Cuvettes (2 to 5)
Safety
Wear goggles and gloves! AgNO3 is corrosive
NaBH4 is flammable and toxic (inhalation, absorption and ingestion)
Sodium Citrate may irritate skin, etc. Hydrogen peroxide is corrosive and
causes burns to eyes, skin etc. Don’t play with the laser pointers!