Dynamics of Excited
States in Nanoscale
Materials
Brian M. Tissue
Department of Chemistry
Virginia Polytechnic Institute and State University
Blacksburg, VA 24061
tissue@vt.edu
Outline
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History and terminology
Materials preparation
Materials characterization
Dynamics
Summary
2
Fire Opal
Chip Clark, http://www.mnh.si.edu/
E. Fritsch et al., The nanostructure of fire opal, J. NonCryst. Solids, 352 (2006) 3957.
3
Natural Nanostructures
Manuka (scarab) beetle
Morpho Butterfly
Andrew R. Parker & Helen E. Townley, Biomimetics of photonic nanostructures, Nature Nanotechnology 2 (2007) 347.
4
Antireflective
Moth Eyes
http://www.asknature.org/
Reflexite display Optics product data sheet
http://www.physorg.com/news122899685.html;
C.-H. Sun, P. Jiang, and B. Jiang, Broadband moth-eye antireflection
coatings on silicon, Appl. Phys. Lett. 92 (2008) 061112
5
The Lycurgus Cup
Late Roman, 4th century AD
(colloidal gold and silver)
Reflected light
Transmitted light
Copyright Trustees of the British Museum, http://www.britishmuseum.org.
6
Michael Faraday 1857

...mere variation in the size
of its particles gave rise to a
variety of resultant colours.

The state of division of
these particles must be
extreme; they have not as
yet been seen by any power
of the microscope.
M. Faraday, The Bakerian Lecture: Experimental Relations of
Gold (and Other Metals) to Light,, Phil. Trans. R. Soc. Lond., 147
(1857) 145.
http://aveburybooks.com/faraday/catalog.html
7
Monolayer Films
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Benjamin Franklin (1771) dropped ‘not more
than a Tea Spoonful’ of oil onto Clapham Pond
Lord Rayleigh (1890) calculated film thickness to
be 1.6 nm
Agnes Pockels, Surface Tension, Nature 43
(1891) 437.
1930s Langmuir-Blodgett films
1940 Katharine Blodgett anti-reflective glass
8
Working Definition of Nanoscale


fine particles: 100 to 2500 nm
nanomaterials: one or more dimensions
between 1 and 100 nm
 ultrafine
particles, nanoparticles, nanocrystals,
quantum dots (semiconductors)
 nanocubes, nanosheets, nanoplates, nanowires,
nanoflowers, etc.
 nanorods (solid), single-walled and multi-walled
nanotubes (hollow)

clusters: few to hundreds of atoms
9
http://cobweb.ecn.purdue.edu/~janes/whats_nano.htm
10
Nanoscale Descriptors

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by medium: colloids, aerosols, hydrosols
by number of phases: nanocomposite
by construction: nanoarrays, nanostructures
(often on surface)
aspect ratio: length-to-width
size distribution:
<
±10 %: monodispersed
 > ±10 %: polydispersed
L.B. Kiss et al., The real origin of lognormal size distributions of nanoparticles in
vapor growth processes, Nanostruct. Mater. 12 (1999) 327-332.
11
Nanocomposites/Nanostructures
http://www.nrccnrc.gc.ca/eng/news/nrc/2003/07/03/nanocomposites.html
T. C. Chong et al., Laser precision
engineering: from microfabrication to
nanoprocessing, Laser & Photon. Rev. 4
(2010) 123.
12
Nanoparticles are Composites
Andrew Maynard, NIOSH and Yasuo Ito,
Argonne National Lab, NSF Workshop Report
on “Emerging Issues in Nanoparticle Aerosol
Science and Technology (NAST)” University of
California, Los Angeles, June 27-28, 2003.
13
Materials Preparation

Bottom-up (chemical)
 easier

to scale up
Top-down (physical)
 precise
control of
dimensions and proximity

Hybrid (scaffolding)
14
Bottom Up
gas-phase
 inert-gas
condensation
 spray pyrolysis
 pulsed-laser
deposition
condensed-phase
 homogeneous
precipitation
 seed-mediated
growth
 self-assembly
(micellar)
 sol-gel
 glass-ceramic
15
Controlling Nucleation and Growth
NSF Workshop Report on “Emerging Issues in Nanoparticle Aerosol Science and Technology (NAST)” University of California,
16
Los Angeles, June 27-28, 2003.
Top Down
lithography
 block copolymer
patterning
 optical interference
 electron beam
(scribing)
contact
 embossing/molding
 pattern transfer
 dip pen lithography
M. Volatier et al., Extremely high aspect ratio GaAs and GaAs/AlGaAs nanowaveguides
fabricated using chlorine ICP etching with N2-promoted passivation, Nanotech. 21 (2010) 134014.
17
Light Well: ATunable Free-Electron
Light Source on a Chip
related to Smith–Purcell effect
G. Adamo et al., Phys. Rev. Lett. 103 (2009) 113901.
18
Materials Characterization

Small angle X-ray
scattering
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Electron microscopy

Scanning probe
microscopy
I review for J. Lumin.
19
X-ray Scattering at APS
grazing-incidence small-angle X-ray
scattering (GISAXS)
ultrasmall-angle X-ray scattering
(USAXS)
2 nm
Z. Jiang et al., Capturing the Crystalline Phase of TwoDimensional Nanocrystal Superlattices in Action, Nano
Lett. 10 (2010) 799–803.
F. Zhang, et al., Quantitative Measurement of Nanoparticle Halo
Formation around Colloidal Microspheres in Binary Mixtures,
Langmuir 24 (2008) 6504-6508.
20
Imaging Methods
1−103
10−106
500−108
Veeco Instruments, Application Note AN48.
21
HRTEM: Defects in BN Sheet
red:
green:
yellow:
blue:
boron
nitrogen
carbon
oxygen
O.L. Krivanek et al., Atom-by-atom structural and chemical analysis by annular dark-field electron microscopy,
Nature 464 (2010) 571.
22
HRTEM: Citrate-capped gold n.p.
2 nm
Z. Lee et al., Direct Imaging of Soft-Hard Interfaces Enabled by Graphene, Nano Lett. 9 (2009) 3365.
23
SEM Cathodoluminescence (1)
X. Zhou et al., The Origin of Green Emission of ZnO Microcrystallites: Surface-Dependent Light Emission
Studied by Cathodoluminescence, J. Phys. Chem. C 111 (2007) 12091.
24
SEM Cathodoluminescence (2)
H. Xue, Probing the strain effect on near band edge emission of a curved ZnO nanowire via spatially
resolved cathodoluminescence, Nanotech. 21 (2010) 215701.
25
Scanning Probe Microscopy
(STM, AFM, etc)
Veeco Instruments, Application Note AN48.
26
Chemical Force Microscopy
Y. Sugimoto et al., Chemical identification of individual surface atoms by atomic
force microscopy, Nature 446 (2007) 64.
27
Near-Field Scanning Optical
Microscopy (NSOM)
F. de Lange et al., Cell biology beyond the diffraction limit: near-field
scanning optical microscopy, J. Cell Sci. 114 (2001) 4153.
L. Zhou et al., Direct near-field optical imaging
of UV bowtie nanoantennas, Optics Express 17
(2009) 20301.
28
Dynamics

Quantum dots and FRET

Localized emitter
 structural/proximity
effects
 surroundings effects
 phonon spectrum changes

Plasmonics
I review for J. Lumin. too!
29
Quantum Dot Absorbance
L. Brus, Chemical Approaches to Seminconductor Nanocrystals, J. Phys. Chem. Solids 59 (1998) 459.
30
Quantum Dot Luminescence
A.L. Rogach, Energy transfer with semiconductor
nanocrystals, J. Mater. Chem. (2009) 1208-1221.
M. Jones, G.D. Scholes, On the use of time-resolved
photoluminescence as a probe of nanocrystal
31
photoexcitation dynamics, J. Mater. Chem. 20 (2010) 3533.
Fluorescence Resonant Energy
Transfer (FRET)



donor/acceptor
spectral overlap
distance
dependence
1/d6
dipole-dipole
orientation
A.L. Rogach, Energy transfer with semiconductor
nanocrystals, J. Mater. Chem. (2009) 1208-1221.
32
Quantum dot FRET
A.L. Rogach, Energy transfer with semiconductor nanocrystals, J. Mater. Chem. (2009) 1208-1221.
33
Localized Emitter in a Nanocomposite
12-nm fcc Ni;
P.M. Derlet et al.,
Phys. Rev. Lett. 87
(2001) 205501.

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crystallinity and defect
concentration
dopant concentration




metastable/disordered structure
dopant concentration and distribution
surface proximity
surroundings effects
size-dependent phonon effects
34
Surroundings Effect (spontaneous
transition rate)


7-nm Eu3+:Y2O3
dispersed in
different media
Line assumes
0.23 filling
factor
R.S. Meltzer, Dependence of fluorescence lifetimes of Y2O3:Eu3+ nanoparticles on the
surrounding medium, Phys. Rev. B 60 (1999) R14012.
35
Size Effects on Nonradiative Rates
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dopant segregation
proximity to defects/surface
electron-phonon interaction
phonon density of states (PDOS)
36
Energy Flow in a Nanocomposite
J. Yang et al., Mesoporous Silica Encapsulating Upconversion
Luminescence Rare-Earth Fluoride Nanorods for Secondary
Excitation, Langmuir 26 (2010) 8850.
37
Size-Dependent PDOS
G. Liu, X. Chen, Spectroscopic properties of lanthanides in nanomaterials, in Handbook on the Physics and
Chemistry of Rare Earths, vol. 37, K.A. Gschneidner, Jr., J.-C.G. Bünzli, V.K. Pecharsky, Eds., (2007).
38
Plasmonics
X. Huang, S. Neretina, M.A. El-Sayed, Gold Nanorods: From Synthesis and Properties to Biological and Biomedical
Applications, Adv. Mater. 21 (2009) 4880.
39
Plasmonics
M. Fleischmann, P.J. Hendra A.J. McQuillan,
Raman spectra of pyridine adsorbed at a silver
electrode, Chem. Phys. Lett. 26 (1974) 163-166.
“A glance through the recent literature reveals a
substantial interest in the physics of minute
metal particles.”
J. Appl. Phys., 47 (1976) 2200.
40
Nano Lett. 10(3) 2010
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Composite Au Nanostructures
for Fluorescence Studies in Visible Light
Nanoassembled Plasmonic-Photonic Hybrid Cavity for Tailored
Light-Matter Coupling
Two-Dimensional Quasistatic Stationary Short Range Surface
Plasmons in Flat Nanoprisms
Drude Relaxation Rate in Grained Gold Nanoantennas
LSPR Study of the Kinetics of the Liquid−Solid Phase Transition in
Sn Nanoparticles
Trapping and Sensing 10 nm Metal Nanoparticles Using Plasmonic
Dipole Antennas
41
Energy Transfer Distance Dependence
M. Malicki, et al., Excited-state dynamics and dye–dye interactions in dye-coated gold nanoparticles with varying
alkyl spacer lengths, Phys. Chem. Chem. Phys., 12 (2010) 6267.
42
Size Dependence
J. Zhang, Y. Fu, J.R. Lakowicz, Luminescent Silica Core/Silver Shell Encapsulated with Eu(III)
Complex, J. Phys. Chem. C 113 (2009) 19404.
43
Fluorophore Engineering
Y. Fu, J.R. Lakowicz, Enhanced Single-Molecule Detection using Porous Silver Membrane, J. Phys. Chem. C
114 (2010) 7492.
44
Single Molecule Spectroscopy
S. Kuhn, U. Hakanson, L. Rogobete, and V. Sandoghdar, Enhancement of Single-Molecule Fluorescence
Using a Gold Nanoparticle as an Optical Nanoantenna, Phys. Rev. Lett. 97 (2006) 017402.
45
Summary

The Future
46
Future


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More precise control over size, proximity, and
complexity in nanostructures
<100 nm resolution in optical imaging methods
3-D nanoscale imaging
Engineered excited-state
dynamics
The unexpected
C. L. Degen et al., Nanoscale magnetic
resonance imaging, PNAS 106 (2009) 1313.
47
There's Plenty of Room at the Bottom:
An Invitation to Enter a New Field of Physics
Richard Feynman, 1959.
...possible (I think) for a physicist to synthesize any
chemical substance that the chemist writes down.
Give the orders and the physicist synthesizes it.
How? Put the atoms down where the chemist says,
and so you make the substance. The problems of
chemistry and biology can be greatly helped if our
ability to see what we are doing, and to do things
on an atomic level, is ultimately developed–a
development which I think cannot be avoided.
48
Thanks!
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