Transcript September 23, 2011 LAB 3 LIGHT & NANOTECHNOLOGY Background MATERIALS AT THE NANOSCALE.

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 (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
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
PROPERTIES OF LIGHT
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
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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!