Question Bank of Nano-physics
Choose the right answer or Complete each of the following or Put ()or
() questions:
Richard Feynman is the father of nanotechnology, with a talk entitled
“There’s Plenty of Room at the Bottom” at the American Physical Society
meeting on California.
Feynman described a process in which scientists would be able to
manipulate and control individual atoms and molecules.
The scanning tunneling microscope STM is an instrument for imaging
surfaces at the atomic level. Its development in 1981 earned its
inventors, Gerd Binnig and Heinrich Rohrer (at IBM Zürich), the Nobel
Prize in Physics in 1986.
The scanning tunneling microscope STM is based on the concept
of quantum tunneling. When a conducting tip is brought very near to the
surface to be examined, a bias (voltage difference) applied between the two
can allow electrons to tunnel through the vacuum between them. The
resulting tunneling current is a function of tip position, applied voltage, and
the local density of states (LDOS) of the sample.
Nanomaterials have a large surface area but their volume is very small.
Nanomaterials are of the dimensions of ≤10-9 m.
Nanomaterials have high melting point compounds.
Nanomaterials were developed for Clean, secure, affordable energy.
Nanomaterials were developed for stronger, lighter, more durable materials.
Nanomaterials were developed for low-cost filters to provide clean drinking
water.
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Nanomaterials were developed for medical devices and drugs to detect and
treat diseases more effectively with fewer side effects.
Nanomaterials were developed for lighting that uses a fraction of the energy
associated with conventional systems.
Nanomaterials were developed for sensors to detect and identify harmful
chemical and biological agents; and Techniques to clean up harmful
chemicals in the environment.
Nanophase Technologies is utilizing nanocrystalline particles, incorporated
into other materials, to produce tough ceramics, transparent sun blocks, and
catalysts for environmental uses, among other applications.
Nanotechnology were developed the space elevator, which is an ultra high
strength materials allow tower to be built into space.
Nanotechnology were developed tiny machines in our body for curing
cancer.
Nanotechnology were developed DNA Computers in a beaker that vastly
outperform our fastest supercomputers.
Nanotechnologies were developed the super strong materials, super
Slippery Materials, tissue engineering, drug delivery, sensors.
Nanotechnology were developed the water proof and oil resistant nanotextile materials
Nanotechnology were developed the Photovoltaic cell and fuel cell.
Carbon Nanotechnologies, has made carbon nanotubes, Fullerene which
have amazing mechanical and electrical properties.
Nanotechnologies were developed the applications of field emission
carbon nanotubes.
Nanotechnologies were developed the applications of field emission of cold
cathode x-ray machines.
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Microfluidic devices are similar to electronic integrated circuits fabricated
using large scale integration.
Microfluidic memory storage devices are similar to random access memory.
The synthesis of nanomaterials includes top-down and bottom-up method.
Scanning Electron Microscope, transmission electron microscope, Atomic
force microscope are various ways for the detection of nanomaterials high
depth.
Spectroscopic methods, X-ray and Neutron diffraction are used for
determination of atomic structure and chemical composition of solid or
liquid nanomaterials.
Scanning Electron Microscope SEM and transmission electron microscope
TEM are used for determination of atomic size and shape for
nanomaterials.
Working with nanoscale requires the impact combination of all traditional
sciences.
The size and dimensions of materials affect materials properties and how we
can use it.
Water at macro-scale is lubricant, while at nano-scale is an adhesive.
The most popular types of forces and Interactions affecting nanoscale
materials are Electrostatic magnetic, gravitational, frictional, chemical,
thermal, quantum, vibration, surface tension and adhesion forces.
Nanofilms are of one-dimensional scale, and nanowires are of twodimensional scale while nanodots are of three-dimensional scale.
Graphite and diamond are two types of the carbon structure.
Superhydrophobic materials – having water contact angle ≥150°
Water repellent surface are achieved by surface nanotexturing and low
surface energy.
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A water-resistant surface inspired by the lotus leaf could enable
applications in microfluidics, underwater coatings, and controlled
deposition.
Polycrystalline grains of metals have various shapes and sizes.
Grain boundaries of metals represent weak spots of less than optimal atomic
packing, where fractures can form and corrosion starts.
Amorphous metals cooled faster than atoms can rearrange into a crystal.
The size distribution, morphology and structure of CdS nanoparticles were
measured by transmission electron microscope (TEM) and x-ray diffraction
(XRD) analysis.
CdS nanoparticles are used in the sporting equipments of high mechanical
strength.
Single wall carbon nano-tubes are used as reinforcing element of
composite materials.
The surfaces of nanotubes are atomically smooth, so their interaction with
the polymer matrix is weak.
One of the most popular transistor in use today, the (MOSFET) MetalOxide-Semiconductor Field Effect Transistor.
Metal-Oxide-Semiconductor Field Effect Transistor are built starting with a
substrate that is doped, or loaded with impurities that give the substrate a
large amount of extra mobile charges.
The famous types of nano-lithography are photolithography, CMOSlithography, soft-lithography, X-ray lithography, projection lithography.
Nanolithography is used to create tiny patterns to lay down “ink” atom by
atom with the aid of Atomic force Microscope tip.
Quantum Mechanics dominates the world of atoms, but typical nanosystems
may contain from hundreds to tens of thousands atoms.
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Many quantum mechanical processes depend on the number of available
energy states per unit energy. This quantity varies with the dimensionality
of the system.
The effective concentration of reactants that are confined in nanostructures
may be very high.
The first laws of quantum physics dealt with energy quantization.
Elementary particles in the physical world like electrons, protons,
neutrons, photons, leptons, hadrons, and field quanta, all have the same dual
particle and wave nature.
Young’s famous double-slit interference experiments that demonstrated that
light were waves.
Electron diffraction from the quasicrystal Al70Co11Ni19 and, electron waves
on the surface of copper detected by scanning tunnel microscopy (STM) are
two strong evidences for the existence of electron waves.
The particle wavelength is inversely proportional to their wave number.
The particle wavelength is inversely proportional to their momentum.
The phase velocity is greater than the group velocity of the wave.
Niels Bohr had postulated in his quantum theory that the angular momentum
of an electron in orbit around the nucleus of the atom is equal to an integer
multiplied with h/2π
The phase velocity was equal to the angular frequency divided by the
wavenumber
Niels Bohr had postulated in his quantum theory that the angular
momentum of an electron in orbit around the nucleus of the atom is equal to
an integral multiplied of h / 2π
In Bottom-up approach a miniaturization of materials components (up to
atomic level) with further self-assembly process leading to the formation of
nanostructures.
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In Top-down approach use larger (macroscopic) initial structures, which
can be externally-controlled in the processing of nanostructures.
The most used top-down approach is photolithography.
Photolithography has been used for a while to manufacture computer chips
and produce structures smaller than 100 nm.
The most recent lithography methods, Printing, stamping, and molding use
mechanical processes instead of photons or electrons. These methods are
normally called soft lithography methods because they involve the use of
polymers.
Bottom-up fabrication techniques includes: Gaseous phase methods,
Liquid phase methods, Solid phase methods and Biological methods
Chemical Vapor Deposition CVD involves the formation of nanomaterials
from the gas phase at elevated temperatures onto a solid substrate or catalyst.
The growth of material layers by Atomic layer Deposition ALD consists of
exposure of the first precursor compound, Purge or evacuation of the
reaction chamber, exposure of the second precursor and Purge of the
reaction chamber.
Vacuum arc deposition is well-established process for producing of thin
films and nanoparticles.
One of the outstanding strides in plasma processing for nanoparticles
synthesis is the developed process of the vapor condensation.
Chemical Vapor Deposition CVD methods have been adapted to make 1-D
nanotubes and nanowires.
Semiconductor quantum wells, superlattices and quantum wires and metallic
or magnetic multilayers for spin valve structures are deposited using
Molecular Beam Epitaxy (MBE).
Sol-gel process consists in the chemical transformation of a liquid (the sol)
into a gel state and with subsequent post-treatment and transition into solid
oxide material.
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The main benefits of sol–gel processing are the high purity and uniform
nanostructure achievable at low temperatures.
Electrodeposition is a long-established way to deposit metal layers on a
conducting substrate.
The principle of electrodeposition is inducing chemical reactions in an
aqueous electrolyte solution with the help of applied voltage, e.g. this is the
process of using electrical current to coat an electrically conductive object
with a relatively thin layer of metal.
Electrodeposition is relatively cheap and can be performed at low
temperatures which will minimize interdiffusion of materials in the case of a
multilayered thin film preparation.
Mask Electrodeposition has been used extensively to pattern
microelectronic metals, semiconductors, and polymers on conductive
substrates.
In a Scan Tunneling Microscope STM only one atom at the end of the tip
carries most of the current. This is the atom that sticks out the most.
In a Scan Tunneling Microscope STM, Negative feedback keeps the
current constant (pA-nA) by moving the tip up and down.
A piezoelectric material changes its length when an electric field is applied.
Vice versa, it generates an Electric field when squeezed or expanded.
The key to vibration damping of is to keep the resonance frequency wo of
the Scan Tunneling Microscope STM as Low as possible (typically 1 Hz).
To obtain an extra sharp Atomic Force Microscope AFM tip one can attach
a carbon nanotube to a regular, micro-machined silicon tip.
In AFM the force is kept constant, while in STM the current is kept
constant.
The STM is particularly useful for probing electrons at surfaces.
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AFM is needed for insulating samples, such as polymers and biomolecules.
A plasmon is a density wave in an electron gas. It is analogous to a Sound
wave, which is a density wave in a gas consisting of molecules.
Plasmons exist mainly in metals, where electrons are weakly bound to the
atoms and free to move.
plasmon is a collective wave
syncronization.
where billions of electrons oscillate in
An X-ray photon creates many electron-hole pairs in silicon,
whose
number is proportional to the ratio between photon energy and band gap
energy.
Graphite is soft and slippery, brittle, electrical conductor, insoluble in
water, and has very high melting point
Diamond is hard, brittle, insulator, insoluble in water, and has very high
melting point.
Nanocarbons has two famous shapes, Bucky balls and Carbon Nanotubes
(CNT)
The direction of rolling of Carbon nanosheets produce three types of carbon
nanotubes, armchair, zigzag and spiral shapes.
The armchair type of carbon nanotubes has the characteristics of a metals
The zigzag type has properties that change depending on the tube
diameter
The spiral type has the characteristics of a semiconductor
A carbon nanotube (CNT) is a tubular molecule with axial symmetry and
diameter in the nanometer range
A carbon nanotube (CNT) can be considered as a rolled up graphene sheet.
Single Walled CNT (SWCNT) is one-atom-thick CNTs
Multi Walled CNT (MWCNT) is a concentric layers of CNTs
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A carbon nanotube (CNT) can be divided into Single Walled CNT
(SWCNT) or Multi Walled CNT (MWCNT)
A carbon nanotube (CNT) has high electrical current capacity than copper.
A carbon nanotube (CNT) has high thermal conductivity comparable to
pure diamond.
A carbon nanotube (CNT) has high temperature stability than metal wires
in microchips.
Doping materials with a carbon nanotube (CNT) may change electrical
properties hence, it can be used as a sensors.
Carbon nanotubes are the strongest known material.
The mechanical properties of Carbon nanotubes composites are very
strong
Carbon nanotubes has many applications such as water resistant materials
Adding Carbon nanotubes to concrete, increase the tensile strength, and
decrease crack propagation
Carbon nanotubes CNT light bulb filament increase the average efficiency
by 40% higher than that of a tungsten filament.
An electric field applied to the nanotube forces electrons to be emitted from
its tip. This electrical current may be used to detect the mechanical
vibrations of the nanotube, and thus listen to the radio waves.
Semiconducting CNTs have been used to fabricate field effect transistors
(CNTFETs). The electron mean free path in SWCNTs can exceed 1 micron
(this is very large) therefore it is projected that CNT devices will operate in
the frequency range of hundreds of GHz.
Carbon nanotubes can be electrically conductive and due to their small
diameter of several nanometers, they can be used as field emitters with
extremely high efficiency for field emission displays (FED)
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A carbon nanotube (CNT) could be used as a heat sink for chipboards, a
backlight for LCD screens or as a faraday cage to protect electrical devices.
A SQUID is a superconducting interferometer device. Which can be used to
monitor infinitesimally small magnetic fields or currents by using gatetunable carbon-nanotubes (CNT) for the Josephson junctions.
Carbon nanotubes covered in titanium atoms provide a very efficient
method for storing hydrogen.
Artificial muscles have been made from millions of carbon nanotubes.
Like natural muscles, providing an electrical charge causes the individual
fibers to expand and the whole structure to move.
The Energy of a Photon E = h (frequency of light)
All physical objects exhibit both particle and wave like properties. This was
the starting point of quantum mechanics developed independently by
Werner Heisenberg and Erwin Schrodinger.
According to the Quantum World it is impossible to know the position and
velocity of a particle with certainty at a given time.
A quantum dot is a
portion of
matter
(e.g. semiconductor
whose excitons are confined in all three spatial dimensions).
A quantum dot materials have electronic properties intermediate between
those of bulk semiconductors and those of discrete molecules
A quantum dot can be visualized as a well. Electrons, once trapped inside
the dot, do not alone possess the energy required to escape.
Quantum dots are nanostructures created from standard semiconductor
materials of 3D quantum wells.
Quantum dots exhibit energy quantization effects even at distances several
hundred times larger than the material system lattice constant.
The band gap is the energy difference between the top of the valence band
and the bottom of the conduction band in insulators and semiconductors.
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The density of states of an ideal quantum dot is discrete, like an atom.
Quantum dots are ordered collections of hundreds to thousands of
semiconductor-type atoms. The electrons associated with a dot are confined
to this small set of atoms.
Quantum
dots
exhibit
fluoresce
in
different
colors.
Schrödinger equation is an equation for finding a particle’s wave function
(x) along the x-axis.
In Quantum dots, the size of the bandgap is controlled by adjusting the
size of the dot.
Energy of a photon E=h=hc/
ZnSe Quantum dots emits at the ultraviolet wavelength spectrum; CdSe
and CdTe are wavelengths that are visible to the human eye; while InAs is
at the infrared spectrum.
Quantum dots are manufactured in a two-step reaction process in a glass
flask, Nucleation and Growth.
light emitting diodes (LEDs); solid state white light, lasers, displays,
memory, cell phones, and biological markers are applications of Quantum
dots.
Functionalized quantum dots can target cancer tumors. The surgeon can see
the glowing tumor, and use it as a guide for more accurate tumor removal.
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The quantum dots can be Functionalized Photovoltaic solar cell, they
engineered to absorb a specific wavelength of light or to absorb a greater
portion of sunlight based on the application.
Quantum Dot Laser allows for higher efficiencies and brighter lasers
because you have better control of photon energies.
With quantum dots, the size of the bandgap is controlled simply by
adjusting the size of the dot
Give the Scientific term of
The photoelectric effect: small energy particles of light, the so-called light
quanta, are able to knock out electrons from metals just like one billiard ball
hitting another.
Waves are disturbances through a medium (air, water, empty vacuum), that
usually transfer energy.
The phase velocity of the wave (V) is directly proportional to the angular
frequency, but inversely proportional to the wavenumber.
The group velocity is the velocity at which the energy of the wave
propagates.
The group velocity is equal to the derivative of the angular frequency with
respect to the wavenumber.
Explain briefly the Metal-Oxide-Semiconductor Field Effect Transistor
(MOSFET) fabrication structure and explain their operation, clarify your
answer with a schematic diagram of IV characteristic curves.
Mention the types of synthesis of nanomaterials by top-down method.
Mention the types of synthesis of nanomaterials by bottom-up method.
Mention the ways of detection of the high depth for nanomaterials
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-Optical Microscope, Scanning Electron Microscope, transmission electron
microscope, Atomic force microscope.
Mention the types of forces and Interactions affecting nanoscale materials.
Mention the famous types of nano-lithography?
-photolithography, CMOS-lithography, soft-lithography, X-ray lithography,
projection lithography
The physics of the nanometer scale tends to become dominated by quantum
physics.
Derive de Broglie wave equation for a nano-particles of wavelength 𝜆 (𝜆 =
ℎ
𝑃
) ,and mass m moving with the speed of light c, and has momentum P
using Einstein’s equation 𝐸 = ℎ𝑓 and Planck’s equation 𝐸 = 𝑚𝑐 2 for
energy.
Using the principal of conservation of energy, derive Schrodinger equation
of the total energy for a particle of mass m and momentum P moving with
velocity 𝑣 associated with a wave of wavelength 𝜆 and wave number 𝑘 .
Compare between Bottom-up approach and Top-down approach with
respect to, beginning pattern, cost, mas production
Draw a schematic diagram for nano-particle condensations in inert gas
Draw a schematic diagram illustrating the general steps for Physical Vapor
Deposition (PVD).
Explain briefly the atomic layer deposition for nanoparticle preparation
method, state the main steps, and clarify your answer with drawings.
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State the principal of Chemical Vapor Deposition (CVD), then draw a
schematic diagram for the conventional (CVD).
Electrodeposition is a long-established way to deposit metal layers on a
conducting substrate. Describe it briefly with draw.
Draw a schematic diagram for Scanning Tunneling Microscope (STM)
describes the xyz-Piezo-Scanner, probing tip, high voltage amplifier and the
feedback regulator.
Draw a schematic diagram comparing between the densities of States g(E)
and energy E of 3D bulk, 2D quantum well, 1D quantum wire and
0Dquantum dot
Write down the Schrödinger equation for finding a particle’s wave function
(x) along the x-axis confined in a box of length from 0 to L. Draw and
mention the Quantized allowed energy levels, which are found by solving
the Schrödinger equation.
Solve the problems:
1) What are the de Broglie wavelengths of electrons with the following
values of kinetic energy? (a) 1.0 eV and (b) 1.0 keV. (me = 9.11 x 10-31 kg,
1eV= 1.6 x 10-31J)
2) What is the de Broglie wavelength of a 50 kg person traveling at 15 m/s?
(h = 6.6 x 10-34 Js) comparable to spacing
3) A sodium vapor light street light emits bright yellow light of wavelength
= 589 nm. What is the energy change for a sodium atom involved in this
emission? How much energy is emitted per mole of sodium atoms? (h = 6.6
x 10-34 Js, c= 3 x 108 m/s, NA= 6.023 x 1023 /mole)
4) A compact disc player uses light with a frequency of 3.85 x 1014 per
second. What is this light’s wavelength? What portion of the
electromagnetic spectrum does this wavelength fall? What is the energy of
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one mole of photons of this frequency? (h = 6.6 x 10-34 Js, c= 3 x 108 m/s,
NA= 6.023 x 1023 /mole)
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