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Carbon Nanotube-Polymethine Dye Complexes with Strong Photoluminescence
William Abbot
Nuffield Foundation
• “Improve social well-being through education, research and innovation”
• Nuffield Research Placements – funding to experience a research project environment
www.nuffieldfoundation.org/nuffield-research-placements
Carbon Nanotubes
• Essentially a rolled-up graphene sheet• Single-wall and multi-wall varieties• Different properties based on how they are rolled up:
metallic or semiconducting
http://www.physik.uni-regensburg.de/aktuell/KollSS05/Thomsen-Vortrag.htm
Uses of Carbon Nanotubes• Materials, composites• Electronics• Novel methods of drug delivery
Aim of the Project
• Carbon nanotubes have a huge range of uses• Problem with potential toxicity• A fast, reliable but portable sensor will be
required
Photoluminescence (Fluorescence) in Single-Wall Nanotubes
Left: From Photoluminescence on Carbon NanotubesRight: www.photon.t.u-tokyo.ac.jp
Energy band gap of SWNTs depends on nanotube diameter: the larger the diameter, the smaller the band gap
The Photoluminescence Spectrum
www.originlab.com
• Each peak (bright spot) a carbon nanotube with different wrap angle/diameter
S
NN
S
C2H5C2H5X
_
+ ( )n
n = 1, 2, 3, 4, 5
Polymethine Dyes
Absorption depends on the length of the chain (the size of n)
Weighing the material
Graphite flake
SDBS - surfactant
Ultrasonication, 20 kHz, 1.25 hours
Centrifugation,30kRPM, 2 hours
Mixingwith DOB-719
(dye)
H2O
Carbon nanotube powder
Method
Spectroscopic analysis
Results
900 1000 1100 1200 1300300
400
500
600
700
800
Emission Wavelength (nm)
Exc
itatio
n W
ave
len
gth
(n
m)
Initial CNT sample
3000
4000
5000
6000
7000
8000
9000
10000
11000
Inte
nsity
900 1000 1100 1200 1300300
400
500
600
700
800
Emission Wavelength (nm)
Exc
itatio
n W
ave
len
gth
(n
m)
CNT+DOB-719 (0.0001mg/ml)
3000
4438
5875
7313
8750
10188
11625
13063
14500
Inte
nsity
Several new peaks at an excitation wavelength of ~735nm appear for CNT+DOB-719
Carbon Nanotube-Dye Interaction
More efficient, so increases intensity of emitted light
Carbon Nanotube-Dye Interaction
900 1000 1100 1200 1300300
400
500
600
700
800
Emission Wavelength (nm)
Exc
itatio
n W
ave
len
gth
(n
m)
CNT+DOB-719 (0.0001mg/ml)
3000
4438
5875
7313
8750
10188
11625
13063
14500
Inte
nsity
Conclusion
• Carbon nanotubes: very promising but potentially harmful
• Fluorescence enhancing probes for carbon nanotubes are being developed
• Will soon lead to sensor systems
Thanks for Listening
www.nuffieldfoundation.org/nuffield-research-placements