Biomedical Engineering Reference
In-Depth Information
structure. 48 Each CNT has a speciic luorescence spectroscopy. It was found
that the emission-excitation spectrum of each type of CNT is speciic. As
described by the following equations, the wavelength ( λ 11 , λ 22 ) and frequency
( υ 11 , υ 22 ) of emission and excitation are closely related with the diameter
and chiral angle of CNTs, where d t is the tube diameter and α is the tube
chiral angle. Other constants include Planck's constant h , speed of light c ,
C-C bond distance a CC and the interaction energy between the neighbouring
C atoms, γ 0 .
λ 11 = hcd t
2 α cc γ 0 λ 22 = hcd t
_______
_______
4 α cc γ 0
157.5 + 1066.9 d t + A 1 cos(3 α )
1 × 10 7 cm -1
____________________
____________
υ 11 =
t
d 2
145.6 + 575.7 d t + A 1 cos(3 α )
1 × 10 7 cm -1
__________________
____________
υ 22 =
t
d 2
Furthermore, by combining the two-dimensional excitation-emission
luorimetric spectrum and resonance Raman data, the optical transition can
be attributed to a speciic ( n , m ) nanotube structure (Table 7.1).
Table 7.1 Spectral data and assignments for SWNTs (modiied from Kam et al. 49 )
Predicted*
υ RBM (cm -1 )
Observed
υ RBM (cm -1 )
Assignment
λ 11
λ 22
(5, 4)
833
483
372.7
373
(6, 4)
873
581
335.2
(9, 1)
912
693
307.4
(8, 3)
952
663
298.1
297
(6, 5)
975
567
307.4
(7, 5)
1023
644
281.9
283
(10, 2)
1053
734
265.1
264
(9, 4)
1101
720
256.4
(8, 4)
1113
587
278.3
(7, 6)
1122
647
262.1
264
(9, 2)
1139
551
289.7
(12, 1)
1171
797
237.0
236
(8, 6)
1172
716
243.7
(11, 3)
1197
792
232.8
233
(9, 5)
1244
671
241.4
(10, 3)
1250
633
251.1
251
(10, 5)
1250
786
225.1
225
(11, 1)
1263
611
256.4
(8, 7)
1267
728
228.9
 
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