February 2, 2005

Surface Electronic Structure Photoemission

Spectroscopy

Optical Characterization of Semiconductor

quantum dotsThin Film Growth

and Characterization

Carbon NanotubesXRD with high pressure Diamond Anvil Cell

Raman and Photoluminescence Spectroscopy of fullerenes

under high pressure

Electro-optical Properties of Polymer-based materials

Sharma’s Research Group

February 2, 2005

GRADUATE STUDENTS:Robert Ramsey, PhD (graduated 12/06)Tonmoy Chakraborty

UNDERGRADUATES:Jay MurphreeChance HarenzaDanielle Williams

February 2, 2005

February 2, 2005

H-PDLC Grating Formation • Hologram Preparation (Interference Geometry for Transmission Grating)

• Hologram Preparation (Interference Geometry for Reflection Grating)

IB

IA

kA

kB

x x

I

λ

Λ

x

z

kA

kB

q 2θset 2θset y

ITO GlassMonomer/LC Syrup

H-PDLC Sample

IB

IA

kA

kB

x x

I

λ

Λ

x

z

kA

kB

q 2θset 2θset y

February 2, 2005

Holographic-PDLC R. A. Ramsey and S. C. Sharma, Opt. Lett. 30 (2005)

20 30 40 50 60 70 80 90 100 110 120 130 140 150 160

0.0

0.2

0.4

0.6

0.8

1.0

m=1m=0

Nor

mal

ized

Sig

nal (

A U

)

o

Typical H-PDLC Switchable Diffraction Pattern

Diffraction Efficiencies During Cure Process

0 5 10 15 20 25 30 35 40 45 50 550

10

20

30

40

50

60

70

80

Diff

ract

ion

Effi

cien

cy ()

Time (minutes)

Incident-Angle Variation (m=1)

February 2, 2005

PDLC-Photonic Crystals (2005)

a = 6.7μm

d = 4.3μm

a = 6.7μm

n ≈1.78

n =1.54

February 2, 2005

February 2, 2005

February 2, 2005

Quantum Dot Size and Emission Wavelength

February 2, 2005

1200 1400 1600 1800 2000 2200 24000.0

0.2

0.4

0.6

0.8

1.0

1.2

09/27/05 Data Taken using Green Laser (514nm, 30mW)E

mis

sion

Inte

nsity

Wavelength (nm)

PbSe_1 (Evident Technologies) PbSe_2

February 2, 2005