EFFECT OF ULTRAVIOLET RADIATION ON STRUCTURAL PROPERTIES OF NANOWIRES
ity-defense062309
1. Nano materials Optoelectronics Laboratory
IMS
Chirality dependent replacement of Flavin
Mononucleotide onto Carbon Nanotubes
using various Surfactants
Ity Sharma
June 23, 2009
Department of Chemistry,
University of Connecticut
4. Physico-Chemical
Large Surface Area (~1600 m2
/g)
Amenable to electrochemical doping
Thermal conductivity twice as good as
diamond (2000 W/m/K)
Good thermal stability (750°C in air,)
Electrical
Metallic or Semiconducting (1-D)
met-SWNTs are ballistic conductors
(109
A/cm2
)
Mechanical
Strongest known fiber (Young’s modulus, ~1
TPa)
Highly flexible, Buckle-prone
Large aspect ratio (~103
)
SWNTSWNT Unique PropertiesUnique Properties
Nanoelectronics, Nanosized Conductors
•Field emission displays
•Electromagnetic Shielding
•Atomic Force Microscope (AFM) tips
• Nanometric test tubes
•Advanced Composites
•Actuators
•Specialty Sensors
•Hydrogen storage
•Cancer therapy
5. Aggregation Dispersion
Separation
Diameter Chiraity
van der Waals binding energy of 500 eV per micrometer
of tube-tube contact
An individual fullerene nanotube in a cylindrical SDS
micelle
Handedness
Challenges
Length
Hersam, M. C., Nature Nanotechnology, 3, 387 (2008).
6. Cross sectional model of
A) Individual carbon nanotube in a cylinderical
SDS micelle
B) A seven –tube bundle coated by a layer of SDS
Emission spectrum (red) of individual fullerene
nanotubes suspended in SDS micelles in D2O, overlaid
with the absorption spectrum (blue) of the sample in
this region of first van Hove band gap transitions.
M. O’Connell et al., Science 297, 593 (2002).
Dispersion of SWNTs using SDS (Sodium dodecyl sulfate)
A
7. Fluorescence has been observed directly across the band gap of semiconducting carbon nanotubes
good spectroscopic route for finding the detailed composition of bulk nanotube samples
Schematic density of electronic states for a
single nanotube structure.
Contour plot of fluorescence intensity versus excitation
and emission wavelengths for a sample of SWNTs
suspended in SDS and deuterium oxide.
Photoluminescence : Important tool for nanotube
characterization
S.M. Bachilo et al Science 298 (2002) 2361.
M. O’Connell et al., Science 297, 593 (2002).
8. poly(9,9-dioctylfluorenyl-2,7-diyl),
(PFO)
Binding model of a (10,0) DNA wrapped
carbon nanotube*
Molecular mechanics simulations of the
polymer, PFO wrapping mechanism#
.
*Zheng, M. et al. DNA-assisted dispersion and separation
of carbon nanotubes. Nature Mater. 2, 338–342 (2003)
Selective enrichment of carbon nanotubes using non
covalent polymer wrapping
#
Nish, A., Hwang, J.-Y., Doig, J. & Nicholas, R. J., Highly
selective dispersion of single-walled carbon nanotubes
using aromatic polymers. Nature Nanotech. 2, 640–646
(2007)
polymeric nature of DNA and
PFO hinders post-separation
surfactant removal
9. The long d-ribityl
phosphate side groups
of FMN provide aqueous
solubilization.
1:4:4 (HiPCO:FMN:D2O)
SWNT dispersed with FMN and centrifuged at 15 kg for 2hrs.
Selection of carbon nanotubes with specific chiralities using helical
assemblies of flavin mononucleotide (FMN)*
Flavin
mononucleotide
(FMN)
Top view of isoalloxazine
moieties wrapped in an
8, 1 helical pattern.
This helical wrapping is stabilized by
cooperative hydrogen bonding
between adjacent flavin moieties
charge transfer interactions
between FMN and graphene side wall.
*
S.-Y. Ju, J. Doll, I. Sharma, F. Papadimitrakopoulos, Nature Nanotech. 3, 356
(2008).
H-bonded
ribbon
10. Photoluminescence Excitation Spectra (PLE) of HiPco-SWNTS
a PLE map of HiPco
SWNT dispersed with
SDBS centrifuged at
200kg
b SWNT dispersed
with FMN and
centrifuged at 15 kg
c After the addition
of 7.4mM of SDBS to
b
d Plot of ES
11 and ES
22
transitions for FMN
and SDBS dispersed
SWNTs.
11. The sigmoidal profiles were fit using Hill equation
Ka=Relative affinity of FMN-SWNT to SDBS
γ =Breadth of sigmoidal curve , indicating how fast SDBS
replaces FMN helix
2.81
1.51
1.33
a–d, PLE maps of FMN-dispersed nanotubes upon
addition of 0 (a), 2.3 (b), 4.3 (c) and 7.4mM (d) SDBS.
a–c, SBDS-derived PL intensity as a function
of SDBS concentration. Red curves are based
on Hill equation fitting
Elucidation of the selective affinity of the FMN helix on
different chirality nanotubes using SDBS
12. a, PLE map of the (8,6) nanotube in the salt-out
supernatant.
b, UV-vis-NIR spectra of the corresponding salt-
out supernatant (black solid line), compared with
the initial FMN-dispersed HiPco sample (red solid
line).
(i) selective SDBS replacement of FMN on all but (8,6)-SWNTs, and
(ii) addition of NaCl to salt out all SDBS-dispersed nanotubes
Enrichment of the (8,6) nanotube
13. Absorbance spectrum showing ES
11 semiconducting region of
FMN dispersed carbon nanotubes titrated with SC
concentrations 0 to 12mM
Sodium cholate, SC
Chirality dependent FMN replacement onto single
walled carbon nanoubes using Sodium Cholate*
#
Schematic depicting the arrangement of sodium cholate around
a (6,5) SWNT.
Purple, red, gray, blue, and white atoms represent Na, O, C (as
part of sodium cholate), C (as part of nanotube), and H.
*Ity Sharma, Sang-Yong Ju and Fotios Papadimitrakopoulos, MRS, 2008, Boston,
Session JJ15: Poster Session: Nanowires and Nanotubes: Electrical, Optical and Thermal properties
#Michael S. Arnold et al, ACS Nano, 2008, 2 (11), pp 2291–2300
14. a PLE map of HiPco SWNT dispersed with SC
centrifuged at 13 kg
b SWNT dispersed with FMN and centrifuged at 15 kg
c After the addition of 4.8mM of SC
d Plot of ES
11 and ES
22 transitions for FMN (red circle)
and SC (blue square) dispersed SWNTs.
Chirality dependent FMN replacement onto single walled
carbon nanoubes using Sodium Cholate
15. Chirality, family and modality dependence of FMN induced
E11
S
red shift for all PLE observed carbon nanotubes
16. 16
(n , m) Diamete
r nm
Chiral
angle
E11
S
E22
S
Ka
SC
γ SC
(8,3) 0.782 15.30 962 667 1.20 25.23
(7,6) 0.895 27.46 1128 650 1.31 28.07
(9,4) 0.916 17.48 1116 725 1.25 21.18
(8,6) 0.966 25.28 1183 720 2.83 10.42
(9,5) 0.976 20.63 1256 673 1.59 20.45
Table showing relative affinity (Ka) of FMN-SWNT wrapping
against SC concentration and fitted Hill equation
SC-PL inensity profiles for(8,6), (9,4) and (8,4)
as a function of SC concentration
PLE map of (8,6) SWNT showing FMN replacement by SC
titration
Elucidation of the selective affinity of the FMN helix on
different chirality nanotubes using SC
17. 17
Small diameter carbon nanotubes there is preference for near
zig zag carbon nanotubes binding with FMN
Large diameter nanotubes near arm chair are more favorable
Plot between binding constant Vs Diameter of SWNT
Interpolated lines follow distinct
color coded family (2n+m =
constant)and modality [(n-m)/3=1
or 2] patterns
18. 18
Conclusion
Flavin mononucleotide demonstrates the strongest binding constant with
(8,6) single walled carbon nanotube in terms of sodium cholate replacement as
in the case of SDBS replacement.
Red shift observed for the first and second optical transition energies
between SC-HiPco and FMN-dispersed single walled carbon nanotubes
resembles that of SDBS.
There is a gradual blue shift on addition of sodium cholate to FMN dispersed
carbon nanotubes as in the case of SDBS.
The tight conformation of sodium cholate provides higher Ka (binding
constant) and γ values. This gives the platform for better enrichment of (n,m)
carbon nanotubes in the sample.
