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where H z is the magnetic field projection alon the crystal hexagonal axis andH F = H x F iH y .A. Zeeman EffectOne can see from Eq. (37) that the magnetic field leads to Zeeman splittingof the double-degenerate exciton states. For the ground dark-exciton statewith angular momentum projection F2 this spliting, D e 2 = e 2 e 2 , can beobtained directly from Eq. (37):De 2 ¼ g cx;2 l B H cos h Hð38Þwhere g ex,2 = g e 3g h and h H is the angle between the nanocrystal hexagonalaxis and the magnetic field directions.Considering the magnetic field terms in Eq. (37) as a perturbation, wedetermine the Zeeman splitting of the optically active F = F1 state:De U 1 ¼ eU 1 e U 1 ¼ l BH z f½ðC þ Þ 2 ðC Þ 2 Šg e ½ðC þ Þ 2 þ 3ðC Þ 2 Šg h gDe L 1 ¼ eL 1 e L 1 ¼ l BH z f½ðC Þ 2 ðC þ Þ 2 Šg e ½ðC Þ 2 þ 3ðC þ Þ 2 Šg h gð39ÞThis splitting (linear in the magnetic field) is proportional to the magneticfield projection H z on the crystal hexagonal axis. Substituting Eq. (21) for C Finto Eq. (39), one can get the dependence of this splitting on the NC radius:De U;L1¼ g U;Lex;1 l BH cos h H ;wherepffiffiffiffiffiffiffiffiffiffiffiffiffig U ex;1 ¼ g f 2 fe pffiffiffiffiffiffiffiffiffiffiffiffiffig 2 þ d fh pffiffiffiffiffiffiffiffiffiffiffiffiffif 2 þ d f 2 þ dpffiffiffiffiffiffiffiffiffiffiffiffiffið40Þg L ex;1 ¼ g f 2 fe pffiffiffiffiffiffiffiffiffiffiffiffiffig 2 þ d þ fh pffiffiffiffiffiffiffiffiffiffiffiffiffif 2 þ d f 2 þ dThere is no splitting of the F = 0 optically active exciton state. In large NCs,for which one can neglect the exchange interaction (g D, g U ex,1 c ( g e + 5g h )/2and g L ex,1 c ( g e 3g h )/2. The average Zeeman splitting for a system of randomlyoriented crystals isDe U;Lex;1 ¼ gU;L ex;1 l BH; De ex;2 ¼ g ex;2l B H22for the F = F1 U,L and F = F2 states, respectively.ð41ÞCopyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
B. Recombination of the Dark Exciton in Magnetic FieldsOne can see from Eq. (37) that components of the magnetic field perpendicularto the hexagonal crystal axis mix the F = F2 dark-exciton states with therespective optically active F = F1 bright-exciton states. The dark-excitonstate with F = 0 is also activated due to its admixture with the F = F1 brightexcitonstates. In small NCs, for which the level splittings are on the order of10 meV, even the influence of strong magnetic fields can be considered as aperturbation. The case of large NCs for which g is of the same order as l B g e Hwill be considered later. The admixture in the F = 2 state is given byDC 2 ¼ l BHg pffiffipffiffi!eC 3 gh C þ2 e 2 e þ C þ 1 þ 3 gh C þ g e C þC1e 2 e 1 ; ð42Þ1where the constants C F are given in Eq. (21). The admixture in the F = 2exciton state of the F = 1 exciton state is described similarly.This admixture of the optically active bright-exciton states allows theoptical recombination of the dark exciton. The radiative recombination rateof an exciton state F can be obtained by summing Eq. (24) over all lightpolarizations [30]:1¼ 4e2 xn rs jFj 3m 2 0 c3 t jh0jpˆlj ˜C F ij 2 ;ð43Þwhere x and c are the light frequency and velocity, respectively, n r is therefractive index, and m 0 is the free-electron mass. Using Eqs. (26) and (28), weobtain the radiative decay time for the upper exciton state with F = 0,1¼8xn rP 2 Ks 0 9 137m 2 ð44Þ0 c2for the upper and lower exciton states with jFj = 1, correspondinglypp ffiffiffiffiffi !1s U;L1¼ 2 ffiffiffiffiffiffiffiffiffiffiffiffiffif 2 þ d b f Fpffiffiffiffiffiffiffiffiffiffiffiffiffi2 f 2 þ d3d1s 0ð45ÞUsing the admixture of the jFj = 1 states in the jFj = 2 exciton given by Eq.(42), we calculate the recombination rate of the jFj = 2 exciton in a magneticfield [3],1s 2 ðHÞ ¼ 3l2 B H2 sin 2 ðh H Þ 2g þ D 218D 2 2g h g e3g s 0ð46ÞThe characteristic time s 0 does not depend on the NC radius. For CdSe,calculations using 2P 2 /m 0 = 19.0 eV [31] give s 0 = 1.5 ns.Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
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Copyright 2004 by Marcel Dekker, In
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This book covers several topics of
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esult, some exciting topics were no
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3. Fine Structure and Polarization
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9. III-V Quantum Dots and Quantum D
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ContributorsUri BaninThe Hebrew Uni
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1‘‘Soft’’ Chemical Synthesi
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structure of energy states leads to
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growth can proceed by Ostwald ripen
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Figure 3 Transmission electron micr
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Figure 4 Temporal evolution of the
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No. 26, are f85% (Fig. 6) [21]. Alt
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tion spectra and broad PL spectra.
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ing surface-to-volume ratio with di
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Figure 8 Photoluminescence spectra
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lattice mismatch. Such a large latt
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match between InAs and ZnS of f11%.
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successfully repeated for up to thr
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Under a different growth regime, on
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Figure 14 Atomic model of the CdSe
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‘‘Teardrop-shaped’’ particl
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Figure 17 High-resolution TEMs of C
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allows isolation of tetrapods in f8
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ligand concentrations yield a reduc
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een determined and quantitatively c
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tion volumes were also shown to be
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synthesis temperatures of z400jC ar
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Figure 23 (a) Photoluminescence spe
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levels (fV1 Mn per NQD). Despite in
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Figure 25 X-ray diffraction pattern
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Figure 27 Transmission electron mic
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An additional factor that strongly
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Figure 30 (a,b) Schematics illustra
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Slow, controlled precipitation of h
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Figure 34 Schematic illustrating th
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achieving biological compatibility
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47. Yu H.; Gibbons P.C.; Kelton K.F
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2Electronic Structure inSemiconduct
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Figure 2 (a) Simple model of a nano
Page 88 and 89: electron and hole to be treated as
Page 90 and 91: independently, Eq. (13) is commonly
Page 92: a better description of the bulk ba
Page 95 and 96: investigated. For optical experimen
Page 97 and 98: Figure 4 (a) Absorption (solid line
Page 99 and 100: Figure 6 Normalized PLE scans for s
Page 101 and 102: Figure 8 A simplistic model for des
Page 103 and 104: Figure 10 Theoretically predicted p
Page 105 and 106: Figure 12 Schematics depicting the
Page 107 and 108: Figure 14 Calculated band-edge exci
Page 109 and 110: Figure 15 Absorption (solid line) a
Page 111 and 112: Figure 18 (a) Calculated band-edge
Page 113 and 114: IV.BEYOND CdSeA. Indium Arsenide Na
Page 115 and 116: the six-band Luttinger Hamiltonian.
Page 117 and 118: 11. Norris, D.J.; Efros, Al.L.; Ros
Page 119 and 120: 69. Gaponenko, S.V.; Woggon, U.; Sa
Page 121 and 122: formation of a long-lived dark exci
Page 123 and 124: where the constant A is determined
Page 125 and 126: In crystals for which the function
Page 127 and 128: The respective wave functions areC
Page 129 and 130: passive, as was shown in Ref. 12. T
Page 131 and 132: square of the matrix element of the
Page 133 and 134: where e F = e F ieV and e F F = e x
Page 135 and 136: see that for all nanocrystal shapes
Page 137: optical recombination of the excito
Page 141 and 142: where x = cos h and f = l B g e H/3
Page 143 and 144: The theory of the polarization memo
Page 145 and 146: Figure 7 The size dependence of the
Page 147 and 148: state would have an infinite lifeti
Page 149 and 150: crystal axis [see Eq. (40)]. As a r
Page 151 and 152: time of the exciton momentum relaxa
Page 153 and 154: One must also account for the influ
Page 155 and 156: observed in one of the first studie
Page 157 and 158: REFERENCES1. Bawendi, M.G.; Wilson,
Page 159 and 160: 4Intraband Spectroscopyand Dynamics
Page 161 and 162: The solid line in Fig. 1 shows the
Page 163 and 164: Figure 2 FTIR spectra of n-type CdS
Page 165 and 166: of the center frequency. The experi
Page 167 and 168: limit given by radiative relaxation
Page 169 and 170: from a long lifetime due to the pho
Page 171 and 172: are two natural approaches to study
Page 173 and 174: 32. Inoshita, T.; Sakaki, H. Physic
Page 175 and 176: continuous spectral tunability over
Page 177 and 178: function and envelope function mome
Page 179 and 180: ottleneck’’ [14,28]. Further re
Page 181 and 182: in NQDs is dominated by nonphonon e
Page 183 and 184: Figure 4 Dynamics of the IR postpum
Page 185 and 186: Figure 5 (a) Time-resolved PL spect
Page 187 and 188: Figure 6 (a) The time delay of the
Page 189 and 190:
and due to Auger-type e-h interacti
Page 191 and 192:
Figure 9 Dynamics of the 1S bleachi
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significantly greater than the fast
Page 195 and 196:
Figure 11 (a) Pump-intensity-depend
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NQD size. For small NQD sizes (R =
Page 199 and 200:
Figure 14 Nonlinear absorption/gain
Page 201 and 202:
sorption change associated with a s
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where n h em is the hole ‘‘emit
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ultrafast (subpicosecond to picosec
Page 207 and 208:
Figure 18 Schematic of transitions
Page 209 and 210:
Figure 19 Dynamics of pump-induced
Page 211 and 212:
where n i (i=1, 2 . . . , N ) is th
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Figure 21 (a) Two-e-h-pair (biexcit
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the volume fraction (filling factor
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intensity dependence of this peak (
Page 219 and 220:
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can contribute to the saturation of
Page 223 and 224:
Page 225 and 226:
coupling between ‘‘volume’’
Page 227 and 228:
numerous discussions on the photoph
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53. Kang, K.; Kepner, A.; Gaponenko
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the ‘‘on-off ’’ emission in
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parallel form of data acquisition i
Page 235 and 236:
Figure 3 (a) Spectral time trace of
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transition energies. In fact, these
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distribution (dark line) does not d
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exposure to only room light. In our
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statistics for the off times are in
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230Shimizu and BawendiCopyright 200
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Figure 10 (a) Time trace of a CdSe(
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and excited QD core states to fluct
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arrows indicate the on-time truncat
Page 253 and 254:
W. K. Woo and V. C. Sundar for assi
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size allows the electron affinity a
Page 257 and 258:
II.THEORY OF ELECTRON TRANSFER BETW
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For the specific case of charge tra
Page 261 and 262:
dominates, the mobility is often fi
Page 263 and 264:
where the constant A and the temper
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components of modulation which are
Page 267 and 268:
nanocrystals [41], understanding ph
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and ionization potential through tw
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quantum dots. Furthermore, because
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For many applications, a host mater
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form blends with morphologies that
Page 277 and 278:
Figure 11 Photoluminescence efficie
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Figure 12 (a) Room-temperature PIA
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discussed briefly in Section IV. Ch
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dithiolates to thiol-terminated DNA
Page 285 and 286:
Films of passivated CdSe nanocrysta
Page 287 and 288:
Figure 16 Photocurrent action spect
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decay with stretched exponential ki
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siderably larger than might be esti
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dispersing CdSe nanocrystal chromop
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memory and charge storage effects [
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all) of the optically excited elect
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composites of nanocrystals and conj
Page 301 and 302:
55. Asbury, J.B.; Hao, E.C.; Wang,
Page 303 and 304:
108. Morgan, N.Y.; Leatherdale, C.A
Page 305 and 306:
The approaches to fabrication of se
Page 307 and 308:
Figure 1 Experimental realization o
Page 309 and 310:
Due to this voltage division, the m
Page 311 and 312:
Figure 3 Simulated tunneling spectr
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electron charging. In both positive
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Figure 5 shows the typical features
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Figure 7 Map of levels for InAs nan
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Figure 8 Scanning electron microsco
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D CB = 0.31 eV is thus obtained. On
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Figure 11 Correlation of optical an
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atomistic approach based on pseudop
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charging indicated that the tunneli
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capacitance values were also kept t
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could not be detected in the QD/DT/
Page 333 and 334:
Figure 18 Tunneling conductanceF sp
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data in the inset of Fig. 19 repres
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corresponding to the s-like wave fu
Page 339 and 340:
7. Grabert, H.; Devoret, M.H., Eds.
Page 341 and 342:
66. Su, B.; Goldman, V.J.; Cunningh
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dimensional confinement are created
Page 345 and 346:
Figure 1 Transmission electron micr
Page 347 and 348:
The room-temperature absorption and
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narrower in samples with larger mea
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GaInP 2 QDs from a plot of the squa
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crystal, indicating lattice-matched
Page 355 and 356:
Figure 5 Evolution of Stranski-Kras
Page 357 and 358:
Page 359 and 360:
Page 361 and 362:
C. Efficient Anti-Stokes Photolumin
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Because HF treatment has been shown
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intensity of the PL when it is on a
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eV stems from recombining carriers
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Figure 16 Model to explain two-colo
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although this term is not rigorousl
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10 ps (about an order of magnitude
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electron relaxation is inhibited an
Page 379 and 380:
Page 381 and 382:
QDs, the nature of the QD capping s
Page 383 and 384:
QD solution. For an interdot distan
Page 385 and 386:
emission spectra of the two individ
Page 387 and 388:
Figure 23 Change of the PL intensit
Page 389 and 390:
(viz. the absorbed light intensity)
Page 391 and 392:
Figure 25Impact ionization in QDs.m
Page 393 and 394:
prevent electron-hole recombination
Page 395 and 396:
36. Miller, R.D.J.; McLendon, G.; N
Page 397 and 398:
91. Vurgaftman, I.; Singh, J. Appl.
Page 399 and 400:
139. Mićić, O.I.; Ahrenkiel, S.P.
Page 401 and 402:
10Synthesis and Fabrication of Meta
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Figure 2 (A-C) Progression of HR-TE
Page 405 and 406:
Figure 3 Schematic for gold nanocry
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Nanocrystal growth can occur by two
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on the other hand, provide an ensem
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Figure 6 (a) SAXS patterns for disp
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Figure 8 The gold nanocrystal film
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of the stabilizing ligand, and the
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successfully modeled the 2D island
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2. Steric Stabilization and a Soft
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are fully extended. Moving away fro
Page 423 and 424:
Figure 11 High-resolution SEM image
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Figure 13 (A) Transmission electron
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function of the density of localize
Page 429 and 430:
Figure 15 High-resolution SEM image
Page 431 and 432:
thiol-capped nanocrystals [2]. The
Page 433 and 434:
41. Ackerson, B.J. Nature 1993, 365
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with the effect of the particle com
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Figure 1a shows the surface plasmon
Page 439 and 440:
Figure 2 (a) Ultraviolet-visible ab
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agents [34]. The short-wavelength b
Page 443 and 444:
Figure 4 (a) Plot of the plasmon ab
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the framework of traditional Mie’
Page 447 and 448:
show that effects due to the surrou
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is located at the position of the g
Page 451 and 452:
Page 453 and 454:
Figure 8 Ultraviolet-visible absorp
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laser pulses while being mixed in t
Page 457 and 458:
Figure 10 shows HR-TEM images of go
Page 459 and 460:
Page 461 and 462:
final irradiation product. At the s
Page 463 and 464:
following the laser excitation appe
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36. Papavassiliou, G.C. Prog. Solid
Page 467 and 468:
particles to expand. Because the he
Page 469 and 470:
was frequency doubled in a 1-mm B-
Page 471 and 472:
Figure 2 Frequency of the acoustic
Page 473 and 474:
Figure 3 Change in radius (DR/R) ve
Page 475 and 476:
In this model, the electrons couple
Page 477 and 478:
Figure 5 Transient bleach data for
Page 479 and 480:
Figure 7 (a) Transient bleach data
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that the particles with >80% Au hav
Page 483 and 484:
3. Del Fatti, N.; Valle´e, F.; Fly
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