The document provides an overview of characterization techniques for nanoparticles. It discusses how characterization refers to studying the features, composition, structure and properties of materials. Nanoparticles are defined as particles between 1 to 100 nanometers in at least one dimension. Their small size results in unique physical, chemical and biological properties compared to bulk materials. A variety of characterization techniques are described including optical microscopy techniques like dynamic light scattering, electron microscopy techniques like scanning electron microscopy, and other methods like photon spectroscopy. The techniques allow analyzing properties of nanoparticles like size, shape, structure and chemical composition.

1. Welcome
1

2. Advancements in Characterization Techniques of
Nanoparticles
Prithusayak Mondal
Division of Agricultural Chemicals
Chairperson : Dr. Anupama Singh
Seminar Leader : Dr. Suman Gupta
2

3. Characterization refers to the study of material‟s features such as its
composition, structure,& various properties like physical, electrical, magnetic
etc.
Nano = 10-9 (extremely small)
Particle = Small piece of matter
Nanoparticle is a microscopic particle whose size is measured in nanometers
(nm). These particles can be spherical, tubular, or irregularly shaped and can
exist in fused, aggregated or agglomerated forms.
(PAS71: 2005,UK)
3

4. Size ranges of nanoparticles
Nanoparticles are defined as particles that have at least one
dimension in the nanorange (1 to 100nm).
(Maurice & Hochella, 2008)
4

5. “To understand the very large, we must
understand the very small.”
- Democritus (400 BC)
5

6. Classification
Nanoparticle
Organic
nanoparticle
Inorganic
nanoparticle
6

7. Novel Properties of nanoparticles
• Small size
• High surface area
• Ease to suspend in liquids
• Deep access to cells and organelles
• Improved physical, chemical & biological properties
 Properties of nanoparticles are different from their bulk counterparts.
 Extremely high surface area to volume ratio results in surface
dependent material properties.
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8. Medical
Agriculture
Information
technology
Energy
Uses
Of
Nanoparticles
Ecology &
environment
Industry
Defence &
security
Consumer
goods
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9. Enhanced catalytic properties of surfaces of nano ceramics or those of noble metals
like platinum and gold are used in the destruction of toxins and other hazardous
chemicals. (Salata, 2005)
Synthesis and characterization of collagen/hydroxyapatite: magnetite nanocomposite material for bone cancer treatment. (Ecaterina et al., 2010)
Antimicrobial effects of silver nanoparticles. (Kim et al.,2007)
Removal of arsenic (III) from groundwater by using different concentration of
nanoscale zero-valent iron (Kanel., 2005).

10. Targeted drug delivery

11. Silver nanoparticles inhibited the binding of the virus to the host cells in vitro
(Elechiguerra et al., 2005).
Cells and S layer protein nanoparticles of Bacillus sphaericus JG A12 have been found
to have special capabilities for the clean up of uranium contaminated waste waters
(Duran et al., 2007).
Magnetosome particles isolated from magnetotactic bacteria have been used as a
carrier for the immobilization of bioactive substances such as enzymes, DNA, RNA
and antibodies (Mohanpuria et al., 2007).
The gold nanoparticles synthesized from E. coli may be used for realizing the direct
electrochemistry of haemoglobin (Du et al., 2007).
Metal nanoparticle embedded paints have been synthesized using vegetable oils and
have been found to have good antibacterial activity (Kumar et al., 2008).
11

12. Nanoparticles in agrochemicals
Nano-encapsulated and solid lipid nanoparticles have been explored for
the delivery of agrochemicals .
(Frederiksen et al., 2003)
The development of organic–inorganic nanohybrid material for
controlled release of the herbicide 2,4-dichlorophenoxyacetate.
(Bin Hussein et al., 2005)
Porous hollow silica nanoparticles, developed for the controlled delivery
of the water-soluble pesticide validamycin with a high loading capacity
(36 wt%), have been shown to have a multistaged release pattern.
(Liu et al., 2006)
The development of a nano-emulsion (water/poly-oxyethylene) non-ionic
surfactant (methyl decanoate) containing the pesticide betacypermethrin.
(Wang et al., 2007)
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13. Characterization Techniques
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14. Optical(Imaging) Probe Characterization Techniques
T
Y
P
E
S
Electron Probe Characterization Techniques
Scanning Probe Characterization Techniques
Photon(Spectroscopic) Probe Characterization Techniques
Ion-particle probe Characterization Techniques
Thermodynamic Characterization Techniques
14

15. Optical(Imaging) Probe Characterization Techniques
Acronym
Technique
Utility
CLSM
Confocal laser-scanning microscopy
Imaging/ultrafine morphology
SNOM
Scanning near-field optical microscopy
Rastered images
2PFM
Two-photon fluorescence microscopy
Fluorophores/biological systems
DLS
Dynamic light scattering
Particle sizing
BAM
Brewster angle microscopy
Gas-liquid interface Imaging
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16. Dynamic light scattering
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17. Basic principle
Particles, emulsions & molecules in suspension undergo Brownian motion.
If the particles are illuminated with laser, the intensity of scattered light
fluctuates.
Analysis of these intensity fluctuations yields the particle size(radius, rk) using
Stokes- Einstein relationship,
rk =kT/6πηD where k = Boltzmann‟s constant
T = Temperature
η = Viscosity
D = Diffusion coefficient
(Movie courtesy of Dr. Eric R. Weeks,
Physics Department, Emory University.)
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18. What does Dynamic Light
Scattering measure?
The diameter measured in DLS is called the hydrodynamic diameter and refers to how a
particle diffuses within a fluid. The diameter obtained by this technique is that of a sphere
that has the same diffusion coefficient as the particle being measured.
The diffusion coefficient will depend not only on the size of the particle “core”, but also on
any surface structure, as well as the concentration and type of ions in the medium.
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19. Instrumentation
Optical
system
Detector
system
DLS
Light
source
Digital
correlator
19

20. Light source
Practical requirements for a sufficiently intense light source demand a narrow-band,
polarized, monochromatic, CW laser.
Type
Wavelength
Power
Size
HeNe
632.8 nm
5-35 mW
0.40- 1.5m
Laser diodes
635-780 nm
5-100mV
0.05-0.15 m
Ar+(air cooled)
488-514.5 nm
~100mW
1m
Ar+(water cooled) 488-514.5 nm
~1.7W
1.5-2m
DPSS (Frequ.
Doubled)
10mV-4W
0.2 -0.5m
532 nm
20

21. Optical system
A lens focuses the laser beam down into the sample which is enclosed in a
temperature-controlled scattering cell surrounded by a refractive index
matching liquid.
The scattered light is focused onto a PMT at an angle 60 by another lens.
Systems like this are constructed on a precision turntable with a stepper
motor, and typically allow experiments to be conducted over a 10 -160
angular range.
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22. Detector system
PMTs are almost universally used as detectors in DLS experiments.
Single photon counting mode (SPCM) which incorporates an avalanche photo diode
(APD), active reset and quenching electronics and a Peltier-type temperature controller
in a small package.
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23. Digital correlator
The ACF is formed by recording the number of photons arriving in each
sample time, maintaining a history of this signal over a large range of sample
times (time series), multiplying the instantaneous and the delayed signal for a
range of time delays & accumulating these products.
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24.  Optical mixing mode : Self beating, homodyning & heterodyning
The typical measurement duration is from 1 to 10 minutes.
 The DLS technique is commonly employed in the range of 0.002 to 2
microns.
 The sample must be a liquid, solution or suspension & very dilute too,
otherwise scattering of light can be unclear.
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25. Advantages
• Measurements are fast, from seconds to minutes.
• Very small quantities of sample can be measured.
• Any suitable suspending liquid (non-absorbing, relatively clear and not
too viscous) can be used.
• The technique is applicable from about 0.001 to several microns.
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26. Disadvantages
• It does not produce a high-resolution histogram of the
size distribution.
• Shape information is not easily obtained.
• Multiple scattering affects the data analysis.
• Dust can make measurement and interpretation
difficult.
26

27. Electron Probe Characterization Techniques
Acronym
Technique
Utility
SEM
Scanning electron microscopy
Raster imaging/topology
morphology
EPMA
Electron probe microanalysis
Particle size/local chemical
analysis
TEM
Transmission electron microscopy
Imaging/particle size-shape
HRTEM
High-resolution transmission electron
microscopy
Imaging structure chemical
analysis
STEM
Scanning transmission electron
microscopy
Biological samples
LEED
Low-energy electron diffraction
Surface/adsorbate bonding
EELS
Electron energy loss spectroscopy
Inelastic electron interactions
AES
Auger electron spectroscopy
Chemical surface analysis
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28. Scanning Electron Microscopy
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29. Basic principle
When the beam of electrons strikes
the surface of the specimen &
interacts with the atoms of the
sample, signals in the form of
secondary electrons, back scattered
electrons & characteristic X-rays are
generated that contain information
about
the
samples‟
surface
topography, composition etc.
29

30. Operation modes
There are 3 modes –
Primary: High resolution (1-5 nm); secondary electron imaging
Secondary: Characteristic X-rays; identification of elemental composition of
sample by EDX technique
Tertiary: Back-scattered electronic images; clues to the elemental composition
of sample
30

31. The typical SEM, the beam passes distribution of scanning
Electronic displayed used to detect & amplify the signals &
In a imagedevices are is therefore athrough pairs map of the
intensity of the deflector on a in from the scanned to
display pairs of an image platescathode ray tube in which of
coils or them as signal being emittedthe electron columnareathe
raster scanning deflect the beam horizontally & vertically.
final lens, whichis synchronized with that of the microscope.
the specimen.
31

32.  The sample must be electrically conductive at the surface.
 Time consuming & expensive.
 Sometimes it is not possible to clearly differentiate nanoparticle from the
substrate.
 SEM can‟t resolve the internal structure of these domains.
 SEM can yield valuable information regarding the purity as well as degree
of aggregation.
32

33. Environmental SEM
In ESEM, samples can be looked at in a low pressure gas environment
While using ESEM it is not necessary to make nonconductive positive
as opposed to a vacuum. GSED posseses as much as a 600-Volt samples
conductive. attract secondary do not need to to desiccated and
bias on it to Materials sampleselectrons compared be the ET SED on a
coated with gold–palladium, for example, and a 300-Volt original
normal SEM, which ordinarily has only as much as thus their positive
characteristics the be preserved for further testing or manipulation.
bias and also may former is relatively far from the sample. Thus the
GSED is set up to collect secondary electrons very efficiently.
33

34. Transmission Electron Microscopy
34

35. Basic principle
The crystalline sample interacts with the
electron beam mostly by diffraction rather
than by absorption.
The intensity of the diffraction depends on
the orientation of the planes of atoms in a
crystal relative to the electron beam.
A high contrast image can be formed by
blocking deflected electrons which produces
a variation in the electron intensity that
reveals information on the crystal structure.
This can generate both „bright or light field‟
& „dark field‟ images.
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36.  TEM enables Direct 2-D imaging of particle size, shape & surface
characteristics.
 Changes in nanoparticle structure as a result of interactions with gas,
liquid & solid-phase substrates can also be monitored.
 Sample must be able to withstand the electron beam & also the high
vacuum chamber.
 Time consuming.
 It needs an analysis by image treatment & must be performed on a
statistically significant large no. of samples.
36

37. HRTEM
HRTEM is an imaging mode of TEM that allows the imaging of the
crystallographic structure of a sample at an atomic scale.
Independent interaction with the sample results the electron wave to pass
through the imaging system of the microscope where it undergoes further
phase change & interferes as the image wave in the imaging plane.
The recorded image is not a direct representation of the samples
crystallographic structure.
It can be used to study local microstructures like lattice fringe, glide plane or
screw axes & the surface atomic arrangement of crystalline nanoparticles.
37

38. TEM comparison
Standard TEM
High resolution TEM
Courtesy of F. Ernst
38

39. Scanning Transmission
Electron Microscopy
This technique works as a mapping device unlike TEM where a stationary,
parallel electron beam is used to form images. In STEM, a fine electron
probe is scanned over a sample. Since it is a serial recording, the image
generation takes longer time as compared to that in TEM.
It combines the ideas of looking at the surface of the sample and into the
sample with an electron beam. STEM is an invaluable tool for the
characterization of nanostructures, providing a range of different imaging
modes with the ability to provide information on elemental composition
and electronic structure at the ultimate sensitivity.
39

40. The STEM works on the same principle as the normal SEM, by forming a
focused beam of electrons that is scanned over the sample while some
desired signal is collected to form an image. The difference with SEM is
that thin specimens are used so that transmission modes of imaging are also
available.
A new possibility is opened up by the new aberration corrected STEMs.
Correcting the lens aberrations allows the objective aperture to be opened
up, thereby obtaining higher resolution. At the same time, as in an optical
instrument aberration corrected STEMs have a depth
Present-daylike a camera, the depth of field is reduced. of field of only a few
nanometers, and so it becomes possible to effectively depth slice through a
sample and to reconstruct the set of images into a 3D representation of the
structure. The technique is comparable to confocal optical microscopy, but
provides a resolution on nanoscale.
40

41. Scanning Probe Characterization Techniques
Acronym
Technique
Utility
AFM
Atomic force microscopy
Topology/imaging/surface
structure
CFM
Chemical force microscopy
Chemical/surface analysis
MFM
Magnetic force microscopy
Magnetic materials analysis
STM
Scanning tunneling microscopy
Topology/imaging/surface
structure
APM
Atomic probe microscopy
Three-dimensional imaging
FIM
Field ion microscopy
Chemical profiles/atomic spacing
APT
Atomic probe tomography
Position sensitive lateral location
of atoms
41

42. Atomic Force Microscopy
42

43. Basic principle
A AFM, a operating parameter is maintained nm) located level & end of
Changes in the tip consisting interaction tip(~ 10 atmonitored using the images
Inparticularprobe specimen of a sharp are often a constantnear an optical
are generated system, in which a loop between the optical detection using
lever detectionthrough a feedback laser is reflected off the cantilever &system
a cantilever beam is raster scanned across the surface of a specimenonto a
& the piezoelectric scanners.
position-sensitive photodiode.
piezoelectric scanners.
43

44. AFM modes
Contact mode
Non-contact mode
Tapping mode
Tip scans in close contact with
surface (repelled)
Constant force
Highest resolution
May damage surface
Tip hovers above the surface
(attracted)
Variable force measured
Lowest resolution
Non-destructive
Intermittent tip contact
Variable force measured
Improved resolution
Non-destructive
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Courtesy of F. Ernst

45. Qualitative analysis
The AFM offers visualization in three dimensions. Resolution in the vertical,
or Z, axis is limited by the vibration environment of the instrument,
whereas resolution in the horizontal, or X-Y, axis is limited by the diameter
of tip utilized for scanning.
Typically, AFM instruments have vertical resolutions of less than 0.1 nm and
X-Y resolutions of around 1 nm.
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46. Figure: Left: NIST traceable polystyrene microspheres from Duke Scientific scanned with the NANO-RP™. Mean
Ø of microspheres is 102nm. Scan size is 1μm x 1μm. Right: 3D view of 1x1μm scan of calibrated spheres
Here 73nm NIST traceable microspheres are shown in both perspective view and top
view. 3D information is incorporated in both views. In the perspective view, the 3D
nature of the image is obvious. In the top view, the intensity of the color reflects the
height of the particle.
46

47. Quantitative analysis
For individual particles, size information (length, width, and height) and other
physical properties (such as morphology and surface texture) can be measured.
Figure: A wood particle scanned with an AFM to measure roughness. Paper products containing such
wood fibers can vary in quality based on the physical properties of the particulates.
47

48. Statistics on groups of particles can also be measured through image
analysis and data processing. Commonly desired ensemble statistics include
particle counts, particle size distribution, surface area distribution and
volume distribution. With knowledge of the material density, mass
distribution can be easily calculated.
Figure: Left: Latex particles outlined and counted.
Right: Particle size distribution of polymer nanospheres.
Mean Ø = 102nm
48

49. Experimental media
AFM can be performed in liquid or gas mediums. This capability can be
very advantageous for nanoparticle characterization. For example, a major
component of the combustion-generated nanoparticles are volatile
components that are only present in ambient conditions.
Dry particles can be scanned in both ambient air and in controlled
environments, such as nitrogen or argon gas. Liquid dispersions of
particles can also be scanned, provided the dispersant is not corrosive to
the probe tip and can be anchored to the substrate.
49

50. Particles dispersed in a solid matrix can also be analyzed by topographical or
material sensing scans of cross-sections of the composite material. Such a
technique is useful for investigating spatial nanocomposites.
Fig: Left: Ni3Al precipitates in a nickel aluminum alloy. 27 μm x 27μm topography image.
Right: 6.8 x 6.8 μm grain particle on super plastic ceramic.
Courtesy of Dr. McCartney group, UCI.
50

51. In many industries, the ability to scan from the nanometer range into the
micron range is important. With AFM, particles anywhere from 1nm to 5μm in
height can be measured in a single scan.
AFM can characterize nanoparticles in multiple mediums including ambient
air, controlled environments & even liquid dispersions.
Less costly & less time consuming.
The roughness of the substrate must be less than the size of nanoparticles being
measured.
51

52. SEM and AFM images
Fig. SEM & AFM images of Cu Nanowires
Courtesy of F. Ernst
R. Adelung et al.
52

53. Scanning Tunneling Microscopy

54. Basic principle
It is based on the concept of quantum tunneling. When a conducting tip is
brought very near to a metallic or semi-conducting surface, a bias between
the two can allow electrons to tunnel through the vacuum between them.
Variations in tunneling current as the probe passes over the surface are
translated into an image.
They normally generate image by holding the current between the tip of the
electrode & the specimen at some constant value by using a piezoelectric
crystal to adjust the distance between the tip & the specimen surface.
54

55. Fig. Highly oriented pyrolytic graphite
sheet under STM
Lateral resolution ~ 0.1 nm
Depth resolution ~ 0.01 nm
STM can be used not only in ultra high vacuum but also in air & various other liquid or
gas, at ambient & wide range of temperature.
STM can be a challenging technique, as it requires extremely clean surfaces & sharp
tips.
55

56. Photon(Spectroscopic) Probe Characterization
Techniques
Acronym
Technique
Utility
UPS
Ultraviolet photoemission spectroscopy
Surface analysis
UVVS
UV-visible spectroscopy
Chemical analysis
AAS
Atomic absorption spectroscopy
Chemical analysis
ICP
Inductively coupled plasma spectroscopy
Elemental analysis
FS
Fluorescence spectroscopy
Elemental analysis
LSPR
Localized surface Plasmon resonance
Nanosized particle
analysis
56

57. Ion-particle Probe Characterization Techniques
Acronym
Technique
Utility
RBS
Rutherford back scattering
Quantitative-qualitative
elemental analysis
SANS
Small angle neutron scattering
Surface characterization
NRA
Nuclear reaction analysis
Depth profiling of solid
thin films
RS
Raman spectroscopy
Vibration analysis
XRD
X-ray diffraction
Crystal structure
EDX
Energy dispersive X-ray spectroscopy
Elemental analysis
SAXS
Small angle X-ray scattering
Surface analysis/particle
sizing(1-100 nm)
CLS
Cathodoluminescence
Characteristic emission
NMR
Nuclear magnetic resonance
spectroscopy
Analysis of odd no.
nuclear species
57

58. X-ray Diffraction
XRD can be used to look at various characteristics of the single crystal or
polycrystalline materials using Bragg’s Law ,
nλ = 2d sinθ
The use of XRD is often compared to the microscopy techniques. XRD avoids
issues of representative samples and determining crystals as opposed to particles
as discussed above.
XRD is time consuming and requires a large volume of sample.
58

59. Thermodynamic Characterization Techniques
Acronym
Technique
Utility
TGA
Thermal gravimetric analysis
Mass loss vs. temperature
DTA
Differential thermal analysis
Reaction heats heat capacity
DSC
Differential scanning
calorimetry
Reaction heats phase changes
NC
Nanocalorimetry
Latent heats of fusion
BET
Brunauer-Emmett-Teller
method
Surface area analysis
Sears
Sears method
Colloid size, specific surface area
59

60. Other Important Techniques
 Nanoparticle tracking analysis
 Tilted laser Microscopy
 Turbidimetry
 Field Flow Fractionation
 Hydrophobic interaction Chromatography
 Electrophoresis
 Isopycnic Centrifugation
 Zeta potential measurements
60

61. 61

62. Characterization of curcumin nanoparticles (Jain et al., 2011) for anti-microbial study.
Instruments used :
30 nm
DLS : Malvern Zetasizer S90 series
TEM : Morgagni 268 D from FEI
SEM : Jeol JSM 840 microscope
~2-40 nm
~50 nm
Fig. Size characterization of curcumin nanoparticles (a) DLS (b) TEM (c) SEM image
62

63. Characterization of potato & cassava starch nanoparticles (Szymońska; 2009) using
AFM(Park Scientific Instrument Autoprobe CP II model & the AFM Ultralevers tips of
Veeco).
Fig. High resolution nc-AFM images &
dimensions of potato starch nanoparticles
Fig. High resolution nc-AFM images and
63
dimensions of cassava starch nanoparticles

64. Characterization of a novel photodegradable insecticide nano-imidacloprid (Chi et
al., 2008) .
Imidacloprid (IMI) microcrystals were directly encapsulated with nature
polysaccharides chitosan (CHI) & sodium alginate (ALG) through layer-by-layer
(LbL) self-assembly. The coated colloids were characterized using confocal laser
scanning microscopy (CLSM) and scanning electron microscopy (SEM).
64

65. Fig. Transmission CLSM images of the IMI release process
from the (CHI/ALG)10 microcapsules. (a) Morphologies of
IMI microcrystal before dissolution. (b) Images of IMI
microcrystal in dissolution. (c) Images of polysaccharide
capsules after removal of the crystal cores
Fig. SEM images of IMI microcrystals (a) uncoated, (b)
coated with 5 layers of CHI/ALG, (c) coated with 10 layers
of CHI-ALG.
65

66. Summary
Nanoparticle
- Properties
- Application
Nanoparticle Characterization
- Methods
- Comparative analysis
Case Study

67. Nanotechnology is the essence of molecular synthesis, manipulation, and
manufacturing.
Nanoparticle-based technologies cover different fields, ranging from
environmental remediation, energy generation and most recent applications
in bioscience.
Nanoparticles, are, key components in the development of new advanced
technologies.
16/07/2011
Division of Agricultural Chemicals
67

68. Nanoparticle characterization is necessary to establish understanding and
control of nanoparticle synthesis and applications.
Nanotechnology has a lot of potential as a futuristic approach but would
be largely governed by simultaneous progress in the newer, faster, simpler
& more efficient characterization techniques for nanoparticles.
16/07/2011
Division of Agricultural Chemicals
68

69. Path Ahead
Integration of different techniques for better understanding of
particle characters
AFM with modern probes for attachment with fluoroscent particles
to study rate kinetics/degradation kinetics
Integration of surface morphology based techniques with 3D imaging
techniques
69

70. Than
k
70