1. Extinction Coefficients and Purity
of Single-walled Carbon Nanotubes
Bin Zhao
Haddon Research Group
Departments of Chemistry and
Chemical & Environmental Engineering
Center for Nanoscale Science and Engineering
University of California, Riverside

2. Applications of Carbon nanotubes
the needs of high purity
High strength light weight composites
Nano-electronic
devices
carbon
nanotubes
AFM probes
biology Hydrogen storage
fuel cells
Field emission devices

3. a
b Purity evaluation by using
electron microscopy (SEM)
Give non-quantitative
evaluation of the
purity of SWNTs.
c
Detect samples at 10-12 gram
scale.

4. Energy of Interband transition of SWNTs
M11
1
S22
energy (eV)
0 Semiconducting S11
S11 S22
SWNTs
Absorbance
AA(N)
-1
DOS (a.u.)
AA(I)
1
energy (eV)
metallic
0 M11
SWNTs
-1
DOS (a.u.) AA(S)
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2
(eV)

5. Solution phase near-IR spectra of SWNT samples
0.40 a
0.35
b
0.30
Absorbance
0.25 c
0.20
0.15
0.10
0.05
0.00
8000 10000 12000 14000 16000 18000
-1
Wavenumber (cm )

6. Purity Evaluation of As-Prepared Single-Walled
Carbon Nanotube Soot by Use of Solution-Phase
Near-IR Spectroscopy
reference sample (R)
M. E. Itkis, D. E. Perea, S. Niyogi, S. M. Rickard, M. A. Hamon, H.Hu,
B. Zhao, and R. C. Haddon* Nano lett. 2003, 3, 309.

7. 0.1
R X
AA(S,R) AA(S,X)
Absorbance
0.0
0.4
AA(T,X)
AA(T,R)
0.2
SWNTs: 67%
REFERENCE (R) CARBONACEOUS
IMPURITIES: 33%
0.0
8000 10000 12000 8000 10000 12000
-1
Wavenumber (cm )
AA(S, R) AA(S, X)
= 0.141 = 0.095
AA(T, R) AA(T, X)
Purity of X against R = (0.095/0.141)*100% =67%

8. Controlled Purification of Single-Walled Carbon
Nanotube Films by Use of Selective Oxidation and
Near-IR Spectroscopy
0.12 0.12
M11
0.10 0.10
S22
Absorbance
0.08 0.08
0.06
S11 0.06
0.04 0.04
0.02
O2-292oC-4h
0.02
0.00 0.00
5000 10000 15000 5000 10000 15000
-1 -1
Wavenumber (cm ) Wavenumber (cm )
AP-SWNT Oxidized SWNT
R. Sen, S. M. Rickard, M. E. Itkis, and R. C. Haddon*
Chem. Mater. 2003, 15, 4273.

9. AP-SWNT Oxidized SWNT
0.08 0.08
0.06 0.06
Absorbance
Absorbance
0.04 0.04
AA(T)=278
0.02 0.02
AA(T)=67
0.00 0.00
0.008 0.008
0.004 0.004
AA(S)=17.7
AA(S) =12.8
0.000 0.000
8000 9000 10000 11000 8000 9000 10000 11000
-1 -1
Wavenumber (cm ) Wavenumber (cm )
AA(S)/AA(T) = 0.0635 AA(S)/AA(T) = 0.191
AA(S, OX)/AA(T, OX)
Relative Purity (RP) = = 3.0
AA(S, AP)/AA(T, AP)

10. Nitric Acid Purification of
Single-Walled Carbon Nanotubes
80
60 3M/12h
3M/24h
AP 3M/48h 7M/6h
7M/12h
AP-SWNT
Weight%
40
16M/6h
20 16M/12h
0
20
Weight loss%
40
7M/6h
60
SWNT weight%
Metal weight%
80
Carbonaceous impurities weight%
100 Lost Weight%
H. Hu, B. Zhao, M. E. Itkis and R. C. Haddon 15M/12h
J. Phys. Chem. B. 2003, 107, 13838.

11. Extinction coefficient study of single-walled carbon
nanotubes and other carbonaceous materials
 Solution phase NIR is a powerful tool to assess
carbonaceous purity of SWNTs.
 Demonstration of the applicability of Beer’s law of
carbonaceous materials.
 Effective extinction coefficient study of SWNTs and
carbonaceous materials – a way to estimate the universal
purity of SWNTs.

12. Absorptivity of Functionalized
Dissolution of small diameter
Single-Walled Carbon Nanotubes
single-wall carbon nanotubes
in Solution
in organic solvents
J. A. Bahr, et. al. B. Zhou, et. al.
Chem. Comm. 2001, 193. JPCB 2003, 107, 13588.

13. The NIR spectra of carbonaceous materials
1.0
carbon black MWNT AP-SWNT (EA)
0.8
Absorbance
0.6
0.4
0.2
0.0
10000 15000 20000 25000 10000 15000 20000 25000 10000 15000 20000 25000 30000
1.0
purified SWNT (EA) AP-SWNT (LO) AP-SWNT (HC)
Absorbance
0.8
0.6
0.4
0.2
0.0
10000 15000 20000 25000 10000 15000 20000 25000 10000 15000 20000 25000 30000
-1
Wavenumber (cm )

14. Electronic structures of SWNTs
produced by different methods
HC
LO
Absrobance (a.u.)
EA
S11
S11
S22
M11
S11 S22
M11
S22
M11
1 2 3
Energy (eV)

15. Purity of EA prepared SWNTs (against R-SWNT)
Sample AA(S) AA(T) Purity
(% of R-SWNT)
AP1-EA 101.9 1149.5 63
AP2-EA 50.2 962.2 37
AP3-EA 113.9 1162 70
AP4-EA 13.7 892.1 11
AP5-EA 60.4 1109.8 39
AP6-EA 43.2 960.1 32
P1-EA 158.5 971.6 116
P2-EA 252.3 1348.1 133
P3-EA 208.8 1304 113
133
140 116 113
120
100
Purity (%)
70
80 63
60 39
37 32
40
11
20
0
-EA
-EA
-EA
A
A
A
A
A
A
1-E
2-E
3-E
4-E
5-E
6-E
P1
P2
P3
AP
AP
AP
AP
AP
AP

16. (a) (b)
P1-EA P2-EA

17. The purity of LO SWNTs
0.20
Method 1: 0.15
AA(S, R)
0.10
Absorbance
0.05
AA(B, R)
0.00
AA(S, LO)
0.15
0.10
0.05 AA(B, LO)
0.00
8000 9000 10000 11000 12000 13000
-1
Wavenumber (cm )
AA(S, R) AA(S, LO)
= 0.141 = 0.066
AA(S, R) + AA(B, R) AA(S, LO) + AA(B, LO)
Purity of LO-SWNT = (0.066/0.141)  100% = 47%

18. 0.20
Method 2:
0.15
AA(S, R)
0.10
0.05
Absorbance
AA(B, R)
0.00
AA(S, LO)
0.15
0.10
0.05 AA(B, LO)
0.00
8000 9000 10000 11000 12000 13000
-1
Wavenumber (cm )
AA(S, R) AA(S, LO)
= 0.096 = 0.046
AA(S, R) + AA(B, R) AA(S, LO) + AA(B, LO)
Purity of LO-SWNT = (0.046/0.096)  100% = 48%

19. Purity of carbonaceous materials (against R-SWNT)
Purity
Sample AA(S) AA(T)
(% of R-SWNT)
AP1-EA 101.9 1149.5 63
133
AP2-EA 50.2 962.2 37 140
116 113
AP3-EA 113.9 1162 70 120 101
AP4-EA 13.7 892.1 11
100
Purity (%)
AP5-EA 60.4 1109.8 39
80 70 66
AP6-EA 43.2 960.1 32 63 59
60 47
P1-EA 158.5 971.6 116 39
37
P2-EA 252.3 1348.1 133 32
40
P3-EA 208.8 1304 113 11
20
1
AC 1 831.4 <1
0
HC 138.5 2127.4 49~69
C
-EA
-EA
-EA
O
A
A
A
A
A
A
HC
AC
LO
P-H
1-E
2-E
3-E
4-E
5-E
6-E
P-L
P-HC 165.2 2078.7 55~76
P1
P2
P3
AP
AP
AP
AP
AP
AP
LO 62.6 1252.2 48~48
P-LO 85.4 803.8 92~110

20. 0.35
0.30 M11
0.25 S22
Absorbance
0.20
0.15
0.10
8000 10000 12000 14000 16000
-1
wavenumber (cm )

21. 0.35
0.30 M11
0.25 S22
Absorbance
0.20
AA(S)
0.15
AA(N) AA(T)
0.10 AA(I)
8000 10000 12000 14000 16000
-1
wavenumber (cm )
AA(T)=AA(S) + AA(N) + AA(I)

22. The applicability of Beer’s law of carbonaceous materials
AA
effective spectral absorbance: A =
spectral width of cutoff
A(T) = A(S) + A(N) + A(I)
C(T) = C(NS) + C(I)
A(I) = (I)  C(I)  l
A(N) = (N)  C(NS)  l
A(S) = (S)  C(NS)  l

23. 50
AP1-EA
AP2-EA
AP4-EA
40
Absorbance/Concentration
P1-EA
P2-EA
30
20
10
0
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14
Concentration (mg/mL)

24. 50
AP1-EA
AP2-EA
AP4-EA
40
Absorbance/Concentration
P1-EA
P2-EA
AC
30 CB
MWNT
20
10
0
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14
Concentration (mg/mL)

25. 50
AP1-EA
AP2-EA
AP4-EA
40
Absorbance/Concentration
P1-EA
P2-EA
AC
30 CB
MWNT
HC(S11)
HC(S22)
20 P-HC(S11)
P-HC(S22)
10
0
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14
Concentration (mg/mL)

26. 50
AP1-EA
AP2-EA
AP4-EA
40
Absorbance/Concentration
P1-EA
P2-EA
AC
30 CB
MWNT
HC(S11)
HC(S22)
20 P-HC(S11)
P-HC(S22)
LO
P-LO
10
AP-C60
P-C60
0
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14
Concentration (mg/mL)

27. Beer’s Law: A =   C  l
C = 0.01mg/mL 8.3  10-4 mol/L
500
496
487
450
437
405
400 391
345 349  (S)  (T) 382
Sample 386
350 (Lmol-1cm-1) (Lmol-1cm-1) 364
333
AP1-EA 31 345
289
AP2-EA 15 289
300 AP3-EA 34 288 292
349
AP4-EA
268 4 268
AP5-EA 18 333 301
250 AP6-EA 13 288
261
P1-EA 48 292
P2-EA 76 405
200 P3-EA 63 391
AC 0 261
150 CB - 437
MWNT - 364
194
HC (S11) 118 382
100 HC (S22) 32 496
143
P-HC (S11) 129 386
50 P-HC (S22) 39 487 129
31 LO 15 301 118
34
15 P-LO 20 194 76
0 4 18
48 63
AP-C60 - 13 143
A
A
(T)
P-C60 - 2
1-E
A
0.1
2-E
A
32
3-E
A
4-E
A
39
AP
5-E
-EA
AP
6-E
-EA
AP
-EA
2
AP
AC
AP
15 20
P1
AP
CB
(S)
T
P2
P3
N
1)
2)
1)
MW
(S1
2)
(S2
S1
LO
S2
O
HC
C(
60
P-L
HC
60
C(
-C
P-H
P-C
P-H
AP

28. A(T)=A(S) + A(N) + A(I)
C(T)=C(NS) + C(I)
A(I) = (I)  C(I)
A(N) = (N)  C(NS)
A(S) = (S)  C(NS)
A(T) = (I)  C(I) + [(N) + (S)]  C(NS)
A(T) = (I)  C(T) + [(N) + (S) – (I)]  (S) -1  A(S)
the intercept is (I)  C(T)
the gradient is [(N) + (S) – (I)]  (S) -1.

29. 0.34
0.32
0.30
A(T)
0.28
0.26
0.24
0.22
0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07
A(S)
C = 0.01mg/mL 8.3  10-4 mol/L
(I) = 270  10 L mol-1 cm-1

30. the gradient is [(N) + (S) – (I)]  (S) -1  2
(N)  (S) + (I) = (S) + 270 L mol-1 cm-1

31. Conclusion
 Solution phase NIR is a powerful tool to assess
carbonaceous purity of SWNTs.
 The Effective extinction coefficient of EA produced
SWNTs falls in the range of 268 ~ 391 L mol-1 cm-1 .
 The effective extinction coefficient of carbonaceous
impurities in SWNTs is 270  10 L mol-1 cm-1 (calculation).
 The relationship of extinction coefficient of carbonaceous
contents in EA-SWNTs is:
(N)  (S) + (I) = (S) + 270 L mol-1 cm-1

32. Acknowledgement
Haddon research group
Dr. Robert C. Haddon (advisor)
Dr. Mikhail E. Itkis
Hui Hu
Dr. Rahul Sen
Daniel Perea
Sandip Niyogi
Dr. Elena Bekyarova
James Love
Jingtao Zhang
Shawna M. Rickard