Transcript What is NANO?

 In 1960, the U.S. National Bureau of Standards
adopted the prefix "nano-" for "a billionth".
 Millimicrometer (millimicron)
 mµ
 µµ
 The nanoscopic scale is sometimes marked as the
point where the properties of a material change; above
this point, the properties of a material are caused by
'bulk' or 'volume' effects.
 Iron has ferromagnetism properties .
 IONs have superparamagnetic properties.
 'surface area effects' become more apparent
 Matter with at least one dimension sized from 1 to 100
nanometres.
 Nanosheets
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 Nanoneedles
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 Nanoparticles
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 National Nanotechnology Initiative (INN)
 The manipulation of matter with at least one
dimension sized from 1 to 100 nanometres.
 Richard Smalley
 Nanotechnology is the art and science of building stuff
that does stuff at the nanometer scale.
 Richard Feynman
 American Physical Society meeting at Caltech on
December 29, 1959.
 There's Plenty of Room
at the Bottom .
 Possibility of direct manipulation of individual atoms
as a more powerful form of synthetic chemistry than
those used at the time.
 Molecular Nanotechnology
 K. Eric Drexler
 Gray goo
 Ecophagy
 Iran Nanotechnology Initiative Council (INIC)
 Bonding atoms
with electrons
 Covalent Bond
 Light & NANOtech
 Photon
 Light is made up of itsy-bitsy particles, too small for
anybody to see.
 Isaac Newton
 light is essentially a stream
of particles
 Wave theory
 light had properties similar to a wavelike electric field
traveling with a wavelike magnetic field.
 light can behave in both ways — as a particle and a wave —
it depends on the situation. To describe light traveling from
one place to another, we call on ideas from the wave model.
When you talk about light interacting with matter on the
atomic level, Albert’s photons come into play — and into
nano-research.
 Wavelength
 Light frequency
 Hertz (Hz) per second.
 C=f*λ
 C (Light velocity): 299 792 458 metres per second
≈ 3 × 108 m/s
 f: frequency in cycles per second
 λ: Wavelength in meter
 Wavenumber (spatial frequency)
 The number of waves that exist over a specified
distance (cm)
 Kicking out a photon
 At the atomic level, all excited atoms are emitting
photons.
 A wire designed to let its atoms heat up till they
generate light.
 Studying things that small requires special, deviously
clever instruments that measure certain properties of
matter — for example, spectrometers
 Infrared (IR) spectroscopy
 Infrared (IR) spectroscopy
 Infrared (IR) spectroscopy
 Infrared (IR) spectroscopy
 Infrared (IR) spectroscopy
 Raman spectroscopy
 Raman spectroscopy
 Stokes shift
 Raman spectroscopy
 Raman spectroscopy
 Vibrational microscopy
 Vibrational microscopy
 Vibrational microscopy
 Vibrational microscopy
 Applications in Biology and Medicine
 Diseased tissue research
 Identify chemical differences in plant leaf material
 Identify bacteria using chemical imaging
 Analysis of biomaterial interactions
 Characterize ingredient or coating distribution in
tablets
 Identify counterfeit medications
 Monitor solvent diffusion and active ingredient
dissolution in blends or granules
 Applications in Microbiology
 Ultra Violet-Visible spectroscopy
 The electrons in each type of atom can only absorb
light of certain frequencies.
 The spectrometer measures that frequency of light
that passes through the sample.
• Ultra Violet-Visible spectroscopy
 UV-Vis spectroscopy plays a role in the creation of
nanosensors that can detect a material and identify its
composition by bonding with it (also called
capturing), which changes the nanosensor’s properties
in specific ways that tell the tale.
 Atomic force microscope (AFM)
 Atomic force microscope (AFM) is providing a
topographic image.
 Electrostatic force microscopy
 Magnetic force microscope (MFM)
 Scanning tunneling microscope (STM)
 Scanning tunneling microscope (STM)
 Scanning tunneling microscope (STM)
 It operates in tow modes
constant height mode
2. constant current mode
1.
 Ernst Abbe
 The ability to resolve detail in an object was limited
approximately by the wavelength of the light used in
imaging, which limits the resolution of an optical
microscope to a few hundred nanometers.
 Developments into ultraviolet (UV) microscopes, led
by Köhler and Rohr, allowed for an increase in
resolving power of about a factor of two.
 However this required more expensive quartz optical
components, due to the absorption of UV by glass.
 At this point it was believed that obtaining an image
with sub-micrometre information was simply
impossible due to this wavelength constraint.
 A wide range of magnifications is possible, from about
10 times (about equivalent to that of a powerful handlens) to more than 500,000 times, about 250 times the
magnification limit of the best light microscopes.
 The types of signals produced by a SEM include
secondary electrons (SE), back-scattered electrons
(BSE), characteristic X-rays, light.
 Secondary electron detectors are standard equipment
in all SEMs, but it is rare that a single machine would
have detectors for all possible signals.
 Back-scattered electrons (BSE) are beam electrons that
are reflected from the sample by elastic scattering.
 BSE are often used in analytical SEM along with the
spectra made from the characteristic X-rays, because
the intensity of the BSE signal is strongly related to the
atomic number (Z) of the specimen.
 BSE images can provide information about the
distribution of different elements in the sample.
 Characteristic X-rays are emitted when the electron
beam removes an inner shell electron from the sample,
causing a higher-energy electron to fill the shell and
release energy.
 All samples must also be of an appropriate size to fit in
the specimen chamber and are generally mounted
rigidly on a specimen holder called a specimen stub.
 For conventional imaging in the SEM, specimens must
be electrically conductive, at least at the surface, and
electrically grounded to prevent the accumulation of
electrostatic charge at the surface.
 Fixation: glutaraldehyde sometimes in combination
with formaldehyde
 Post-fixation: osmium tetroxide?
 Dehydration: Because air-drying causes collapse and
shrinkage, this is commonly achieved by replacement
of water in the cells with organic solvents such as
ethanol or acetone, EtOH, 30, 50, 70, 90 & 100%.
 Temperature-sensitive materials such as ice
 Cryo-fixation
 Cryo-stage
 Low-temperature scanning electron microscopy
 Sputter coater
 Higher magnification results from reducing the size of
the raster on the specimen
 Topography: surface features such as texture
 Morphology: shape, size, and arrangements of the
particles that compose the object’s surface
 Composition: elements that make up the sample (This
can be determined by measuring the X-rays produced
when the electron beam hits the sample.)
 Bouncing electrons off a sample is only one technique;
you can also shoot electrons through
 It’s a kind of nanoscale slide projector: Instead of
shining a light through a photographic image (which
allows certain parts of the light through), the TEM
sends a beam of electrons through a sample.
 Max Knoll and Ernst Ruska in 1931