Physics of Nanotubes, Graphite and Graphene Mildred Dresselhaus ...

Quantum Transport and Dynamics in Nanostructures
The 4th Windsor Summer School on Condensed Matter Theory
6-18 August 2007, Great Park Windsor (UK)
Physics of Nanotubes, Graphite and
Graphene
Mildred Dresselhaus
Massachusetts Institute of Technology, Cambridge, MA

Physics of Nanotubes, Graphite
and Graphene
Outline of Lecture 1 - Nanotubes
• Brief overview of carbon nanotubes
•
•
•
•
Review of Photophysics
of Nanotubes
Phonon assisted Photoluminescence
Double wall carbon nanotubes
Nano-Metrology

•
•
Carbon Nanotube researchstill
a growing field
1991 nanotube observation by Sumio Iijima (NEC) opening field
number of publications is still growing exponentially
6000
5000
4000
3000
2000
1000
0
1991 1996 2001 2006
number of publications containing “Carbon Nanotube” vs. time
Iijima, S., Helical Microtubules of Graphitic Carbon. Nature, 1991. 354(6348): p. 56-58.

Carbon Nanotubes
(5,5)
Armchair Nanotube
(9,0)
Zigzag Nanotube
(6,5)
Chiral Nanotube
(n,m) notation focuses on symmetry of cylinder edge

Carbon materials
• Diamond
• Graphite (hexagonal, rhombohedral)
• HOPG (highly oriented pyrolytic graphite)
• Pyrolytic graphite
• Turbostratic graphite
• Kish graphite
• Liquid carbon
• Amorphous carbon
• Carbon and graphitic foams
• Carbon fibers
• Fullerenes
• Nanotubes
• Nanohorns
• Graphene fibers and scrolls
• Graphene
• Graphene ribbons

3D, 2D, 1D Carbon Materials
Diamond
sp 3
(3D) 1332 cm -1
Graphite
sp 2
(2D) 1582 cm -1
sp 1
Chain
(1D) 1855 cm -1
All are Raman active with characteristic frequencies

Unique Properties of Carbon
Nanotubes within the Nanoworld
graphene sheet SWNT
armchair
zigzag
chiral
• Size: Nanostructures with dimensions
of ~1 nm diameter (~10 atoms around
the cylinder)
• Electronic Properties: Can be either
metallic or semiconducting depending on
diameter and orientation of the hexagons
• Mechanical: Very high strength,
modulus, and resiliency. Good
properties on both compression and
extension.
• Physics: 1D density of electronic states
• Single molecule Raman spectroscopy
and luminescence.
• Single molecule transport properties.
• Heat pipe, electromagnetic waveguide.

One Dimensional Systems:
• High aspect ratio
• Enhanced density of states
• Single wall carbon nanotubes SWNT: Nanowire
Chirality and diameter-dependent properties
D. O. S.
E
3D
Bulk Semiconductor
D. O. S.
2D
Quantum Well
D. O. S.
Nanotube
1D
Quantum Wire
D. O. S.
E E E
0D
Quantum Dot

Nanotube Structure in a Nutshell
Graphene Sheet SWNT
Rolled-up graphene layer
Large unit cell.
� � �
C na ma ( n, m)
h
= 1 + 2 ≡ ⎨
⎪ θ =
(4,2)
⎧
⎪
dt ⎪
L a
= =
π π
n + nm + m
⎪ ⎩
−1
3m
tan
2n
+ m
2 2
Each (n,m) nanotube is a unique molecule
R.Saito et al, Imperial College Press, 1998

Electronic structure of a carbon nanotube
Rolling up 2D graphene sheet Confinement of 1D electronic states
1D van Hove singularities -
high density of electronic
states (DOS) at well defined
energies
Graphene ribbons resemble nanotubes in some ways

⎧ 3p
n − m = ⎨
⎩3p
± 1
Metal or Semiconductor ?
R. Saito et al., Appl. Phys. Lett. 60, 2204 (1992)
• Density of States
• Depending on Chirality, Diameter
metal
semiconductor
Each (n,m) nanotube is a unique molecule
Armchair graphene ribbons can be M or S
E ∝1/
d
gap t

Physics of Nanotubes, Graphite
and Graphene
Outline of Lecture 1 - Nanotubes
• Brief overview of carbon nanotubes
•
•
•
•
Review of Photophysics
of Nanotubes
Phonon assisted Photoluminescence
Double wall carbon nanotubes
Nano-Metrology

Resonance Raman Spectroscopy (RRS)
A.M. Rao et al., Science 275 (1997) 187
RRS: R.C.C. Leite & S.P.S. Porto, PRL 17, 10-12 (1966)
• Enhanced Signal
� Optical Absorption
� e-DOS peaks
π π∗
diameter-selective resonance process
ω RBM = α /
d t
Raman spectra from SWNT bundles
E = 0.94eV
= 1.17eV
= 1.58eV
= 1.92eV
= 2.41eV

Resonant Raman Spectra of Carbon Nanotube Bundles
M. A. Pimenta (UFMG) et al., Phys. Rev. B 58, R16016 (1998)
G-band resonant Raman spectra
laser energy
G-band
d t = 1.37 ±
0.18 nm
Diameter dependence of
the Van-Hove singularities

RBM
Single Nanotube Spectroscopy yields E ii
, (n,m ( n,m)
Resonant Raman spectra for isolated single-wall carbon
nanotubes grown on Si/SiO2 substrate by the CVD method
A. Jorio (UFMG) et al., Phys. Rev. Lett. 86, 1118 (2001)
Semiconducting
Metallic
Raman signal from one
SWNT indicates a strong
resonance process
'
Each nanotube has a
unique DOS because of
trigonal warping effects
R. Saito et al.,
Phys. Rev. B 61, 2981
(2000)
(ω RBM
, Eii) �
(n,m)

Raman Intensity
o
RBM: ωRBM∝ 1/dt Raman Spectra of SWNT Bundles
D-band
G-band
G -
G +
Raman Shift (cm −1 )
Metallic G-band
G -
G +
G′-band
•RBM gives tube diameter and diameter distribution
•Raman D-band characterizes structural disorder
•G -
band distinguished M, S tubes and G + relates to charge transfer
•G’ band (2nd order of D-band) provides connection of phonon to its wave vector
G +

Water, 1.1 g/cm3 SDS
Energy [eV]
2
0
–2 0
1.0 g/cm 3
c 1
fluorescence
v 1
1.2 g/cm 3
SDS=Sodium Dodecyl
c 2
absorption
v 2
Density of Electronic States
e-DOS of (n, m) = (10,5)
Band Gap Fluorescence
Sulfate
M. J. O’Connell O Connell et al., al.,
Science 297 (2002) 593
S. M. Bachilo et al., Science 298 (2002) 2361.
Excitation (nm)
Peaks only
Emission (nm)
Initially (n,m) assignments were made by
empirical excitation-emission pattern

PHOTOLUMINESCENCE
SDS-wrapped HiPco nanotubes in solution
S. M. Bachilo et al., Science 298, 2361 (2002)
�2n+m=constant family patterns are observed in the PL excitation-emission spectra
�Identification of ratio problem
�Showed value of mapping optical transitions
Perhaps this technique can be applied to study graphene ribbons

Raman Mapping of a Nanotube
(µm)
G-band @ 1600cm x 10
40
-1
4
20
2
0
0
-20
-2
-40
-4
-60
-6
-80
-8
2.5
2
1.5
1
0.5
-100
-20 0 20 -2 0 2 (µm)
-10
0
(µm)
RBM 40 @ 173cm
4
-1
2
0
-2
-4
-6
-8
20
0
-20
-40
-60
-80
-100
-20 0 20
1000
800
600
400
200
-2 0 2 (µm)
-10
0
(µm)
H. Son et al. unpublished (2006)
4
2
0
-2
-4
-6
-8
Silicon @ 520cm -1
40
20
0
-20
-40
-60
-80
-100
-20 0 20
x 10
9
-2 0 2 (µm)
-10
8
7
6
5
4
3
2
1
0

E 33 S
Resonance Raman Spectroscopy
on the same sample used for PL
E 11 M
RRS
simple tight binding (sTB)
γ 0
E 22 S
sTB
=2.9eV
2n+m = constant
family behavior is
observed
E 33 S
Fantini (UFMG) et al.
PRL (2004) showed
RRS and PL give
the same E ii
E 11 M
E 22 S
The simple TB does not
describe Eii correctly!
Family effects are
mainly due to
trigonal warping

Transition Energy (eV)
EXTENDED TIGHT BINDING MODEL
Inverse Diameter (1/nm)
M 2n+m=3p
S1 2n+m=3p+1
S2 2n+m=3p+2
Kataura plot is calculated within the
extended tight-binding approximation
using Popov/Porezag approach:
�
�
�
curvature effects (ssσ, spσ, ppσ, ppπ)
long-range interactions (up to ~4Å)
geometrical structure optimization
The extended tight-binding
calculations show family behavior
(differentiation between S1 & S2
and strong chirality dependence)
similar to that of the PL empirical fit
Family behavior is strongly influenced
by the trigonal warping effect
Ge.G. Samsonidze et al., APL 85, 5703 (2004)
N.V. Popov et al Nano Lett. 4, 1795 (2004) & New J. Phys. 6, 17 (2004)

Brillouin zone (BZ)
2D graphene BZ
K’
Family
mod (2n+m, 3) =
2n+m families in SWNTs
R. Saito et al., Phys. Rev. B, 72, 153413 (2005)
SWNT BZ
K
type I type II
0 : metal
1 : type I SC
2 : type II SC
(example)
2n+m = const family
type I – type II separation
(8,0), (7,2), (6,4)
→ 2n+m = 16 type I family

Physics of Nanotubes, Graphite
and Graphene
Outline of Lecture 1 - Nanotubes
• Brief overview of carbon nanotubes
•
•
•
•
Review of Photophysics
of Nanotubes
Phonon assisted Photoluminescence
Double wall carbon nanotubes
Nano-Metrology

DNA wrapping of SWNTs
DNA Wrapping:
� provides good separation of
CoMoCAT SWNT sample
Subsequent fractionation:
� results in sample strongly
enriched in (6,5) species
M. Zheng, et al. Science 302, 1546 (2003)
Average DNA helical
pitch ~ 11nm,
height ~ 1.08nm.

column
containing
stationary
phase
DNA-Assisted DNA Assisted SEPARATION
M. Zheng et al., al. , Science, Science,
302,1546 302,1546
(2003).
load
sample
add
eluant
collect
samples
Raman characterization shows
that
•DNA wrapping removes metallic
(M) SWNTs
•Chromatography further removes
M SWNTs preferentially
Ion-exchange chromatography
(IEC)
Hybrid DNA-SWNTs:
• M-SWNT different surface charge density,
higher polarizability, elute before S-CNTs
RBM Spectra Taken at E laser = 2.18eV
CoMoCAT CNT
(No DNA)
DNA-CNT
M
Fractionated DNA-CNT
(6,5)
150 200 250 300 350 400
Raman Shift (cm -1 )
S

•
•
Nanotube PL Spectroscopy
Most Measurements
- excitation at E22, emission at E11 - measured with Xe lamp
- (2n+m) family patterns
provide (n, m)
identifications.
Our Measurements
– (6,5) enriched sample
– Intense light source
(laser)
– Allows observation of
phonon assisted
processes
PL map of SDS-
dispersed HiPco CNTs
Maruyama et al. NJP (2003)
Maruyama’s work suggests study of detailed phonon-assisted
excitonic relaxation processes for different phonon branches.

Excitation Energy (eV)
1.64
1.6
1.56
1.52
1.48
1.44
PL Spectra of (6,5) Nanotubes
1.05 1.1 1.15 1.2 1.25 1.3
Emission Energy (eV)
Phonon-assisted transitions on an expanded scale
Chou, et al PRL 94, 127402 (2005)
8
7.5
7
6.5
6
5.5
5
E 11 = 1.26eV
E 22 = 2.18eV

2-photon excitation to a 2A + symmetry exciton (2p)
and 1-photon emission from a 1A− exciton (1s)
cannot be explained by the free electron model
1A−
E11 (1s)
Excitons
ABSORPTION (a.u.)
Experimental Justification for excitons
2A+
E11 (2p)
BAND-EDGE
1.2 1.4 1.6 1.8 2.0
2-PHOTON EXCITATION ENERGY
The observation that excitation and emission are
at different frequencies supports exciton model
in Carbon Nanotubes
1A−
E 11 (1s)
EMISSION ENERGY
1.4
1.3
1.2`
(7,5)
(9,1)
(8,3)
(6,5)
1.2 1.4 1.6 1.8
2-PHOTON EXCITATION ENERGY
Wang et al. Science 308, 838 (2005)

The exciton-phonon sidebands
E 22 S -E11 S
Sideband
further support exciton
HiPco + SDS solution
F. Plentz Filho (UFMG) et al,
PRL 95, 247401 (2005)
E 11 S -E11 S
model
Perebeinos, Tersoff and Avouris,
PRL 94, 027402 (2005)

Emission Identified with
One and Two Phonon Processes:
2 iLO/iTO near Γ
2 iTO near K (G’ band)
2 iLO/iLA near K
2 oTO near Γ(M-band)
1iLO/iTO near Γ (G-band)
Chou et al., PRL 94, 127402 (2005)
Phonon dispersion relations
of graphite
Two phonon
process
One phonon
process

Non-degenerate Non degenerate Pump-probe
Pump probe
Frequency domain Fast optics, Time domain
S. G. Chou et al. PRL 94 127402 (2005)
E Pump
~E11(6,5) + 2ħωph, D
E probe =E 11(6,5)
Epump = 1.57±0.01eV, ~E11 Eprobe = around E11of (6,5) nanotube
(Instrument resolution ~250fs)
Pump
Intraband
relaxation
Probe
Interband
relaxation
(6,5)+2ħω D
S. G. Chou et al. Phys. Rev. B (2005)

Pump Probe Studies at Special E pump
• Epump = 1.57±0.01eV≈E 1A-
11 (6,5) +2ħωD • Eprobe = around E 1A-
11 of (6,5) nanotube
Pump
Intraband
relaxation
Probe at
band edge
Exciton population at E 1A-
11 (6,5):
• Quick rise (within 200fs)
• Three decay components:
• τfast~680fs (dominant process)
• τint~2-3ps (dominant process)
• τslow~50ps (weak during first
20ps).
K

-Pump at 1.57±0.01 eV
Probing at Different Energies:
1.27eV(8,3)
1.25eV(6,5)
1.22eV
1.20eV(7,5)
1.16eV
Exp. (n,m) E Probe FluenceJ/m 2 fast % Int % Slow %
O 5 (8,3) 1.27eV 0.3 900fs 70 Several ps Traces mixed 30ps 30
O 4 (6,5) 1.25eV 0.3 700fs 45 3ps 45 50ps 10
O 2 (7,5) 1.20eV 0.1 800fs 90 N/A N/A 40ps 10
u
z
0
j
Eii o 5
o4 o3 o2 o1 E11 1A- E
11
(6,
1A- 1A- (8,3
E
11 1A- 1A- (7
E
11 1A- 1A-(7
K
(8,3)+2hwD
6,5) 5)+2hwD
(7,5) ,5)+2hwD
E
11 1A- E
11
(6 (6,5) ,5)
1A- (8.3)
(7,5) ,5)

•
•
Why?
–
–
More on Excitons
Large binding energy (0.5eV)
•
Even at room temperature, excitons
exist.
Exciton specific phenomena
•
dark excitons, two photon, environment
What can we know or imagine?
–
–
Near cancellation by self energy
•
ETB + many body effects reproduce Eii
Localized exciton wave function
•
enhancement of optical process
• Length dependence.
Wang et al. Science
308, 838 (2005)
2+
A 1- 11 (2p)
A11 (1s)

Exciton exists only in the 3M-triangle
E11S
E22S
E44S
E55S
E33S
Energy minima for the π∗
Cutting lines occur around K-point.
band exist only in 3MΔ.

K’
Centre
Symmetry considerations
of mass motion
Relative motion
K
J. Jiang et al. Phys. Rev. B75 035405 (2007)
A symmetry
Γ
K
e h
excitons
:Good quantum number
C 2
K’
K
Bright and dark excitons
Γ
A - : bright exciton
A + , E and E *: dark excitons
K
e h
A ±
e
hK Γ

E symmetry exciton
E exciton
K’
e
K
K
h
K
Bright and dark excitons
A- : bright exciton
A + , E, E *: dark excitons
Dispersion for (6,5) NT
and its dispersion
E* exciton
K’
h
K’
K
e
K

A -
Dark state has the lowest energy
J. Jiang et al. Phys. Rev. B75 035405 (2007)
: bright exciton
11 11 11 11
A- : bright exciton
A + , E and E *: dark excitons
Lowest energy but not symmetry allowed

Physics of Nanotubes, Graphite
and Graphene
Outline of Lecture 1 - Nanotubes
• Brief overview of carbon nanotubes
•
•
•
•
Review of Photophysics
of Nanotubes
Phonon assisted Photoluminescence
Double wall carbon nanotubes
Nano-Metrology

Raman Intensity
o
RBM: ωRBM∝ 1/dt Photophysics
Photophysics
Raman Spectra of SWNT Bundles
D-band
G-band
G -
G +
Raman Shift (cm −1 )
Metallic G-band
G -
G +
G’-band
of SWNTs is now at an advanced stage
of MWNTs (DWNTs) is at an early stage

•
•
•
•
Motivation for studying DWNTs
Applications
–
world shows much interest
Synthesis
–
world has made major progress
Promising for fundamental physics
Study of the interface between DWNTs
and bilayer graphene should enrich
both areas

•
Approaches to DWNTs
simplest assumption
+
=
Suggests using Kataura plots for SWNTs as first
approximation for DWNTs, but E(k) of monolayer and
bilayer graphene say more detail is needed

Br 2 -doped double-wall nanotubes
TEM images
SEM images
5 nm
Pristine DWNTs
(a) (b)
(c) (d)
100nm
5 nm
100nm
Br2-DWNTs Highly pure
samples
(99% of DWNTs
1% of SWNTs +
catalysts
particles)
+
Endo et al. Nanolett.
4,1451 (2004)

Kataura plot: undoped vs. doped SWNTs
using Extended Tight Binding Model
E ii (eV)
2.5
2.0
1.5
Outer tubes
Inner tubes
2.4 2.0
d (nm)
t
1.6 1.2 0.8
E M
11
E S
33
38
39
35
36
E S
22
32
33
31
29
29
30
28
1.0
100 150 200 250 300 350
26
27
26
25
24
23
22
Frequency (cm −1 )
21
E S
11
19
20
18
17
16
Doped
(+0.04 e - /C)
Undoped
• Different
configurations
for outer/inner
nanotubes
depending on
laser energy

Semiconducting outer/Metallic inner configuration
Raman Intensity (arb. units)
• Breathing mode spectrum
from the Br2 dopant
• Resonance with Bromine
electronic transitions
• Can identify individual
(n,m) inner tubes from
Kataura plot
1.4
M
(b)
S
RBM properties at Elaser=2.33 eV
E laser = 2.33 eV
100 150 200 250 300 350
Frequency (cm -1 )
A.Souza-Filho. et al PRB (2006)
Br 2
doped Br -doped
2
Raman Intensity (arb. units)
1.0
(a)
100 150 200 250 300 350
Frequency (cm -1 )
38
35
ELaser= 2.33 eV Pristine
22
32
(12,3)
(11,5)
29
(9,6)
(7,7)
26
27
24
150 200 250
23
Frequency (cm −1 )
(8,5)
(9,3)
21

Raman Intensity (arb. units)
Metallic outer/Semiconducting inner configuration
1.0
Raman Intensity (arb. units)
1.4
100 150 200 250 300 350
Frequency (cm -1 )
3
(a) E laser = 1.58 eV
1.0
(9,4)
240 250 260 270 280
Frequency (cm -1 )
39
S
(10,2)
36
E S
22
*
33
31
M
RBM properties at Elaser=1.58 eV
29
*
(11,0)
28
25
150 200 250
22
Frequency (cm −1 )
pristine
(9,1)
E S
11
• Intensity enhancement after
bromine doping
• Doping changing relative
intensities of (n,m) tubes
• The Kataura plot for SWNTs
gives identification for inner
wall tubes and shows doping effect
(b) E laser = 1.58 eV Br 2 doped
1.4
(9,4)
(10,2)
240 250 260 270 280
Frequency (cm -1 )
*
*
(11,0)
100 150 200 250 300 350
Frequency (cm -1 )

Raman Intensity
Metallic shielding effects
Metallic outer/semiconducting inner wall
E laser =1.58 eV
1500 1550 1600
Frequency (cm
1650
-1 )
1301
D band
D and G band (DWNTs)
1554
1200 1300 1400 1500 1600 1700
Frequency (cm -1 )
Br 2 -doped
Pristine
• The G-band is predominantly from semiconducting
Nanotubes (based on diameter dependence)
• No shift in the G-band for semiconducting inner tubes
• The inner tubes are shielded by the metallic outer tubes
S
M

Raman Intensity
Charge transfer effects
Semiconducting outer/metallic inner
E laser =2.33 eV
x0.5
D band
1341
1200 1400 1600
D and G band (DWNTs)
Pristine
Frequency (cm -1 )
Br 2 -doped
1450 1500 1550 1600 1650
1485
1570
1545
1562
1537
1519
1581
Frequency (cm -1 )
1575
1592
1599
1450 1500 1550 1600 1650
Frequency (cm -1 )
• The G-band profile is a mixing of semiconducting and metallic profiles;
• Shift in the G-band from semiconducting outer tubes indicates charge
transfer to the Br2 molecules
• The BWF (Breit Wigner Fano) decreases after doping.
• The decrease in the overall intensity indicates depletion of states
M
S

Raman Intensity
Charge transfer
(a)
Br 2 doped
Pristine
M S
and
effects
x0.3
E laser
2.33 eV
Raman Intensity
1450 1500 1550 1600 1650
Frequency (cm -1 )
Metallic inner tubes highly
affected by doping
Semiconducting inner tubes
is not affected when shielded by
metallic tubes
(b)
screening
G band Raman spectra of
doped DWNTs.
Br 2
S
M
E laser
1.58 eV
1450 1500 1550 1600 1650
Frequency (cm -1 )

Calculated electronic charge density
difference (ρdoped - ) of DWNTs
ρ undoped
Calculation supports experimental observations about charge transfer
A.G. Souza Filho et al Nano Letters (2007)

Raman Intensity
Outer tubes
Undoping experiments on
bromine doped DWNTs
Br 2 -adsorbed DWNTs
Br 2
Inner tubes
E laser =2.33 eV
100 200 300 400 500
Frequency (cm -1 )
Br 2
Energy
needed
for removing
Br 2
is ~ 25 meV
21 o C
heating
600 o C
cooling
21 o C
• The dopant is completely removed after heat treatment
Souza Filho et al, PRB (2006)

Spectrum for RBM for pristine and
Raman Intensity
H SO doped DWNTs
2 4
Outer Walls M
Inner Walls
H 2 SO 4 doped
Pristine
150 200 250 300 350 400
Frequency (cm -1 )
S
Elaser=2.052 eV
•Outer walls strongly affected by doping
•Inner semiconducting (S) tubes weakly interact with dopant
•Inner metallic (M) tubes more strongly interact with dopant
E. Barros et al, PRB (2007)

•
•
•
What we learned from
intercalation studies of DWNTs
The Kataura plot from SWNTs provides a
semi-quantitive interpretation of frequencies
for inner wall tubes for DWNTs
The M/S configuration shields inner
semiconducting tubes from the effect of the
dopant
The S/M configuration allows charge transfer
to inner metallic tubes
This work potentially relates to bilayer
S
M
M
S
graphene

Laser Energy Dependence of G′-band Spectra
The ~2450 cm-1 peak (TO+LA) in
DWNTs is downshifted relative to
the corresponding peak in SWNTs
The SWNT G’ band corresponds to peak 3 of DWNTs
Frequency (cm -1 )
2700
2650
2600
2550
2500
2450
SWNTs
Some resemblance to bilayer graphene
E. B. Barros et al., PRB in press (2007)
2.186 eV
inner
outer
2400 2600 2800
Frequency (cm -1 )
1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6
Excitation Energy (eV)
4
3
2
1
0

Physics of Nanotubes, Graphite
and Graphene
Outline of Lecture 1 - Nanotubes
• Brief overview of carbon nanotubes
•
•
•
•
Review of Photophysics
of Nanotubes
Phonon assisted Photoluminescence
Double wall carbon nanotubes
Nano-Metrology

The problem of Nano-metrology
Why do we need metrology for nanotechnology?
Why do we need reference standards?
What is new about metrology at the nano-scale?
What does nanoscience
have to do with metrology?
World wide production of Carbon Nanotubes
MWNTs 270 tons/yr (2.45× 10 5 kg/year)
SWNTs 7 tons/yr (6.35 × 10 3 kg/year)
8K US$ / kg to 5.0 × 10 5 US$ / kg
(R. Blackmon, http://www.wtec.org/cnm/)

Potential Applications of Carbon Nanotubes
by M. Endo, M. S. Strano, P. M. Ajayan @ Springer TAP111
Large Volume Applications Limited Volume Applications
(Mostly based on Engineered
Nanotube Structures)
Present - Battery Electrode Additives (MWNT)
- Composites (sporting goods; MWNT)
- Composites (ESD* applications; MWNT)
*ESD – Electrical Shielding Device
Near Term
(less than ten
years)
Long Term
(beyond ten
years)
Metrology is guided by applications
- Battery and Super-capacitor Electrodes
- Multifunctional Composites
- Fuel Cell Electrodes (catalyst support)
- Transparent Conducting Films
- Field Emission Displays / Lighting
- CNT based Inks for Printing
- Power Transmission Cables
- Structural Composites (aerospace and
automobile etc.)
- CNT in Photovoltaic Devices
- Scanning Probe Tips (MWNT)
- Specialized Medical Appliances
(catheters) (MWNT)
- Single Tip Electron Guns
- Multi-Tip Array X-ray Sources
- Probe Array Test Systems
- CNT Brush Contacts
- CNT Sensor Devices
- Electro-mechanical Memory Device
- Thermal Management Systems
- Nano-electronics (FET,Interconnects)
- Flexible Electronics
- CNT based bio-sensors
- CNT Fitration/Separation
Membranes
- Drug-delivery Systems

Quantity
What should we measure? At which scale?
mass Mass Mass remaining Remaining, % (%)
100
90
80
70
60
50
40
30
20
10
0
“Quality”
Statistical Comparison
QCM shows SWNTs
TGA (375 °C)
100
77.90 %
~mg 90 ~µg
1 5 9 13 17 21 25
1 experiment number 25
Experiment Number
are
non-homogeneous already at the μg scale
mass remaining (%)
Mass Remaining, %
80
70
60
50
40
30
20
10
vs.
Thermogravimetric analysis (TGA)
Quartz cyrstal microbalance (QCM)
QCM (375 °C)
75.88 %
0
1 5 9 13 17 21
1 experiment Experiment Number number 25

Can we trust the measurements?
What do we use for measuring nanomaterials properties?
4-PROBES TRANSPORT SCANNING
PROBES
2
R 14 ≠
R 12 +R 23 +R 34
1
3
4
Purewal et al.,PRL 98,186808 (2007)
50nm
From Achim Hartschuh
IBM Website
LIGHT: Raman and photoluminescence
LOCALIZED LIGHT EMISSON
ELECTRON
MICROSCOPY
From Hubert - FEI

Can we trust the measurements?
What is the ideal environment?
Encapsuled by micelles Suspended in air
Sitting on a substrate Within
a forest
Nano-metrology is a wide open area for development requiring collaboration
between metrology and nanoscience experts