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September 23, 2011

September 23, 2011. Background What is nanoscience? What is considered nanoscale? What is the significance?

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Page 1: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

September 23, 2011

Page 2: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

Background

Page 3: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

Background

What is nanoscience? What is considered nanoscale? What is the significance?

Page 4: September 23, 2011. 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)

Page 5: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

Graphene

Nobel Prize in Physics 2010

Andre Geim & Konstantin Novoselov (University of Manchester)

Page 6: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

Carbon Nanotubes (D ~ 4 nm)

Page 7: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

Quantum Dots (5 to 50 nm)

Page 8: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

Gold Nanoparticles

HeLa cells with fluorescent gold nanoparticles

(Dr. Mengxiao Yu and Dr. Jie Zheng – UT Dallas).

Page 9: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

Background

Page 10: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

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).

Page 11: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

Electromagnetic Spectrum

Page 12: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

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

Page 13: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

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.

Page 14: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

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.

Page 15: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

How to separate light

Prism Diffraction

Page 16: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

Figure 5: Diffraction of light (pg 25) w(sinθn) = nλ tan(θn) = yn/L

Page 17: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?
Page 18: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

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.

Page 19: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

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)

Page 20: September 23, 2011. Background  What is nanoscience?  What is considered nanoscale?  What is the significance?

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!