23.2 Nanocrystals: Size and Thermal Effects
455
Table 23.2 Linearization of
the LFR acoustic modes of
various nanosolids
Sample
A (slope)
Ag-(a, b)
23.6 ± 0.72
Ag-c
18.2 ± 0.56
TiO-(a, b)
105.5 ± 0.13
SnO-a
93.5 ± 5.43
CdSe-1-a
146.1 ± 6.27
CdSe-1-b
83.8 ± 2.84
CdSe-1-c
46.7 ± 1.39
CdS-a
129.4 ± 1.18
CdS-b
58.4 ± 0.76
Si
97.77; 45.57; 33.78
Table 23.3 Quantitative information derived from theoretical matching to the measured
temperature and size dependence of the Raman shift for CdSe nanoparticles and nanorods [50]
Input
Output
R
(nm)
A(dω/dT )
d z (nm) E z
(eV)
E coh
(eV)
θ D
(K)
Δω(z)
(cm −1 )
Bulk
∞
0.0142
12
0.2940
0.153
1.84
450
215.0
Dot
7.8
0.0162
9.14
0.2883
0.169
1.57
300
213.0
4.8
0.0168
7.36
0.2824
0.204
1.47
–
211.6
3.1
0.0170
4.81
0.2666
0.250
1.40
–
209.9
Rod
8.0
10.14
0.2906
0.160
1.65
–
213.1
6.0
0.0157
9.52
0.2892
0.164
1.54
–
211.7
3.5
0.0174
7.76
0.2840
0.176
1.42
–
210.1
202
204
206
208
210
212
214
216
Δω (cm
-1
)
T (K)
3.1 nm
4.8 nm
7.8 nm
Bulk
(a)
0
100
200
300
400
0
100
200
300
400
500
202
204
206
208
210
212
214
Δω (cm
-1
)
T (K)
3.5 nm×20 nm
6.0 nm×70 nm
8.0 nm×80 nm
(b)
Fig. 23.6 Theoretical reproduction (solid curves) of the measured (scattered data) [49] temperaturedependent Raman shifts of a CdSe nanoparticles and b cylindrical nanorods of different radius and
lengths derived with information given in Table 23.3. Reprinted with permission from [50]