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allows isolation of tetrapods in f82% yield (compared to 15–40% by theHPA method) at 120jC. Size control is less well developed, and particles arerelatively large compared to their HPA-derived counterparts. Nevertheless, itis the first significant report of solution-based growth of bipod and tripodmorphologies in the II–VI system and provides a more predictable methodof producing tetrapods [41].The same monosurfactant system can be applied to shape-controlledpreparation of the magnetic semiconductor MnS [42]. At low solution-growthtemperatures (120–200jC), MnS prepared from the single-source precursorMn(S 2 CNEt 2 ) 2 can nucleate in either the zinc-blende or the wurtzite phase,whereas at high temperatures (>200jC), MnS nucleates in the rock-saltphase. Low-temperature growth yields a variety of morphologies: highly anisotropicnanowires, bipods, tripods, and tetrapods (120jC), nanorods(150jC), and spherical particles (180jC). The ‘‘single pods’’ comprise wurtzitecores with wurtzite-phase arms. In contrast, the multipods comprisezinc-blende cores with wurtzite arms, where the arms grow in the [001] directionfrom the zinc-blende {111} faces, as discussed previously with respect tothe Cd–chalcogenide system. Dominance of the isotropic spherical particleshape in reactions conducted at moderate temperatures (180jC) implies ashift from predominantly kinetic control to predominantly thermodynamiccontrol over the temperature range from 120jC to 180jC [42]. Formation of1D particles at low temperatures results from kinetic control of relativegrowth rates. At higher temperatures, differences in activation barriers togrowth of different crystal faces are more easily surmounted, equalizingrelative growth rates. Finally, high-temperature growth supports only thethermodynamic rock-salt structure—large cubic crystals. Also, by combiningincreased growth times with low growth temperatures, shape evolution to‘‘higher-temperature’’ shapes is achieved [42].Extension of the ligand-controlled shape methodology to highly symmetriccubic crystalline systems is also possible. Specifically, PbS, having therock-salt structure, can been prepared as rods, tadpole-shaped monopods,multipods (bipods, tripods, tetrapods, and pentapods), stars, truncatedoctahedra, and cubes [43]. The rod-based particles, including the monopodsand multipods, retain short-axis dimensions that are less than the PbS Bohrexciton radius (16 nm) and, thus, can potentially exhibit quantum-size effects.These highly anisotropic particle shapes represent truly metastable morphologiesfor the inherently isotropic PbS system. The underlying PbS crystallattice is the symmetric rock-salt structure, the thermodynamically stablemanifestations of which are the truncated octahedra and the cubic nanocrystals.The PbS particles are prepared by pyrolysis of a single-sourceprecursor, Pb(S 2 CNEt 2 ) 2 , in hot phenyl ether in the presence of a large excessof either a long-chain alkyl thiol or amine. The identity of the coordinatingCopyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
ligand and the solvent temperature determine the initial particle shapefollowing injection (Fig. 19). Given adequate time, particle shapes evolvefrom the metastable rods to the stable truncated octahedron and cubes, withstar-shaped particles comprising energetically intermediate shapes [43].As in the CdSe system, the particle shape in the cubic PbS systemdepends intimately on the ligand concentration and its identity. The highestFigure 19 Transmission electron micrographs showing the variety of shapesobtained from the PbS system grown from the single-source precursor Pb(S 2 CNEt 2 ) 2at several temperatures: (a) Multipods prepared at 140jC; (b) tadpole-shapedmonopod (140jC); (c) I-shaped bipod (140jC); (d) L-shaped bipod (140jC); (e) T-shaped tripod (140jC); (f ) cross-shaped tetrapod (140jC); (g) pentapod (140jC); (h)star-shaped nanocrystals prepared at 180jC; (i) Rounded star-shaped nanocrystalsprepared at 230jC; (j) truncated octahedra prepared at 250jC. (From Ref. 43;reprinted with permission.)Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.
Page 1: Copyright 2004 by Marcel Dekker, In
Page 4 and 5: Copyright 2004 by Marcel Dekker, In
Page 6 and 7: Copyright 2004 by Marcel Dekker, In
Page 8 and 9: This book covers several topics of
Page 10 and 11: esult, some exciting topics were no
Page 12 and 13: 3. Fine Structure and Polarization
Page 14 and 15: 9. III-V Quantum Dots and Quantum D
Page 16 and 17: ContributorsUri BaninThe Hebrew Uni
Page 18 and 19: 1‘‘Soft’’ Chemical Synthesi
Page 20 and 21: structure of energy states leads to
Page 22 and 23: growth can proceed by Ostwald ripen
Page 24 and 25: Figure 3 Transmission electron micr
Page 26 and 27: Figure 4 Temporal evolution of the
Page 28 and 29: No. 26, are f85% (Fig. 6) [21]. Alt
Page 30 and 31: tion spectra and broad PL spectra.
Page 32 and 33: ing surface-to-volume ratio with di
Page 34 and 35: Figure 8 Photoluminescence spectra
Page 36 and 37: lattice mismatch. Such a large latt
Page 38 and 39: match between InAs and ZnS of f11%.
Page 40 and 41: successfully repeated for up to thr
Page 42 and 43: Under a different growth regime, on
Page 44 and 45: Figure 14 Atomic model of the CdSe
Page 46 and 47: ‘‘Teardrop-shaped’’ particl
Page 48 and 49: Figure 17 High-resolution TEMs of C
Page 52 and 53: ligand concentrations yield a reduc
Page 54 and 55: een determined and quantitatively c
Page 56 and 57: tion volumes were also shown to be
Page 58 and 59: synthesis temperatures of z400jC ar
Page 60 and 61: Figure 23 (a) Photoluminescence spe
Page 62 and 63: levels (fV1 Mn per NQD). Despite in
Page 64 and 65: Figure 25 X-ray diffraction pattern
Page 66 and 67: Figure 27 Transmission electron mic
Page 68 and 69: An additional factor that strongly
Page 70 and 71: Figure 30 (a,b) Schematics illustra
Page 72 and 73: Slow, controlled precipitation of h
Page 74 and 75: Figure 34 Schematic illustrating th
Page 76 and 77: Figure 36 Transmission electron mic
Page 78 and 79: achieving biological compatibility
Page 80 and 81: 47. Yu H.; Gibbons P.C.; Kelton K.F
Page 82 and 83: 2Electronic Structure inSemiconduct
Page 84 and 85: 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
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Figure 12 Schematics depicting the
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Figure 14 Calculated band-edge exci
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Figure 15 Absorption (solid line) a
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Figure 18 (a) Calculated band-edge
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IV.BEYOND CdSeA. Indium Arsenide Na
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the six-band Luttinger Hamiltonian.
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11. Norris, D.J.; Efros, Al.L.; Ros
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69. Gaponenko, S.V.; Woggon, U.; Sa
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formation of a long-lived dark exci
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where the constant A is determined
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In crystals for which the function
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The respective wave functions areC
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passive, as was shown in Ref. 12. T
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square of the matrix element of the
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where e F = e F ieV and e F F = e x
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see that for all nanocrystal shapes
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optical recombination of the excito
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B. Recombination of the Dark Excito
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where x = cos h and f = l B g e H/3
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The theory of the polarization memo
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Figure 7 The size dependence of the
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state would have an infinite lifeti
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crystal axis [see Eq. (40)]. As a r
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time of the exciton momentum relaxa
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One must also account for the influ
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observed in one of the first studie
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REFERENCES1. Bawendi, M.G.; Wilson,
Page 159 and 160:
4Intraband Spectroscopyand Dynamics
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The solid line in Fig. 1 shows the
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Figure 2 FTIR spectra of n-type CdS
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of the center frequency. The experi
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limit given by radiative relaxation
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from a long lifetime due to the pho
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are two natural approaches to study
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32. Inoshita, T.; Sakaki, H. Physic
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continuous spectral tunability over
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function and envelope function mome
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ottleneck’’ [14,28]. Further re
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in NQDs is dominated by nonphonon e
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Figure 4 Dynamics of the IR postpum
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Figure 5 (a) Time-resolved PL spect
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Figure 6 (a) The time delay of the
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and due to Auger-type e-h interacti
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Figure 9 Dynamics of the 1S bleachi
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significantly greater than the fast
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Figure 11 (a) Pump-intensity-depend
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NQD size. For small NQD sizes (R =
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Figure 14 Nonlinear absorption/gain
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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
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Figure 18 Schematic of transitions
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Figure 19 Dynamics of pump-induced
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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
Page 217 and 218:
intensity dependence of this peak (
Page 219 and 220:
Copyright 2004 by Marcel Dekker, In
Page 221 and 222:
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
Page 229 and 230:
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
Page 241 and 242:
exposure to only room light. In our
Page 243 and 244:
statistics for the off times are in
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230Shimizu and BawendiCopyright 200
Page 247 and 248:
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
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dominates, the mobility is often fi
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where the constant A and the temper
Page 265 and 266:
components of modulation which are
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nanocrystals [41], understanding ph
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and ionization potential through tw
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quantum dots. Furthermore, because
Page 273 and 274:
For many applications, a host mater
Page 275 and 276:
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
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Films of passivated CdSe nanocrysta
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Figure 16 Photocurrent action spect
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decay with stretched exponential ki
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siderably larger than might be esti
Page 293 and 294:
dispersing CdSe nanocrystal chromop
Page 295 and 296:
memory and charge storage effects [
Page 297 and 298:
all) of the optically excited elect
Page 299 and 300:
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
Page 315 and 316:
Figure 5 shows the typical features
Page 317 and 318:
Figure 7 Map of levels for InAs nan
Page 319 and 320:
Figure 8 Scanning electron microsco
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D CB = 0.31 eV is thus obtained. On
Page 323 and 324:
Figure 11 Correlation of optical an
Page 325 and 326:
atomistic approach based on pseudop
Page 327 and 328:
charging indicated that the tunneli
Page 329 and 330:
capacitance values were also kept t
Page 331 and 332:
could not be detected in the QD/DT/
Page 333 and 334:
Figure 18 Tunneling conductanceF sp
Page 335 and 336:
data in the inset of Fig. 19 repres
Page 337 and 338:
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
Page 343 and 344:
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
Page 351 and 352:
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
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Figure 7 Photoluminescence spectra
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Figure 8 Photoluminescence spectra
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C. Efficient Anti-Stokes Photolumin
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Because HF treatment has been shown
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Page 367 and 368:
intensity of the PL when it is on a
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eV stems from recombining carriers
Page 371 and 372:
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
Page 377 and 378:
electron relaxation is inhibited an
Page 379 and 380:
Figure 18 Transmission electron mic
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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
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(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
Page 403 and 404:
Figure 2 (A-C) Progression of HR-TE
Page 405 and 406:
Figure 3 Schematic for gold nanocry
Page 407 and 408:
Nanocrystal growth can occur by two
Page 409 and 410:
on the other hand, provide an ensem
Page 411 and 412:
Figure 6 (a) SAXS patterns for disp
Page 413 and 414:
Figure 8 The gold nanocrystal film
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of the stabilizing ligand, and the
Page 417 and 418:
successfully modeled the 2D island
Page 419 and 420:
2. Steric Stabilization and a Soft
Page 421 and 422:
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
Page 427 and 428:
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
Page 445 and 446:
the framework of traditional Mie’
Page 447 and 448:
show that effects due to the surrou
Page 449 and 450:
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:
Figure 11 Transmission electron mic
Page 461 and 462:
final irradiation product. At the s
Page 463 and 464:
following the laser excitation appe
Page 465 and 466:
36. Papavassiliou, G.C. Prog. Solid
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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
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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
Page 481 and 482:
that the particles with >80% Au hav
Page 483 and 484:
3. Del Fatti, N.; Valle´e, F.; Fly
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