M.Sc. Materials Science (Semester IV) (CBCS) Examination, 2017
PHYSICS OF NANO MATERIALS
Day Date: Friday, 21-04-2017 Max. Marks: 70
Time: 02.30 PM to 05.00 PM
Instruction Question 1 and 2 are compulsory.
Attempt any three from Q.3 to Q.7
All question carry equal marks.
Q.1 Choose correct answer 08
The surface area to volume ratio of a sphere with radius 30 nm is
108 109 107 106
In bottom up approach the building blocks can be
Atoms molecules clusters all above
If the size of the metal nanoparticles decreases then the position of
the SPR peak
Shifts towards lower wavelength
Shifts towards higher wavelength
Remain same
None of the above
If an electron is confined in limited space then the allowed energy
states are
Continuous discrete Limited None
The basic principle of AFM is
change in force due to change in distance
change in current due to change in distance
change in shape due to change in distance
change in size due to change in distance
In SEM the morphology of the sample is achieve with the help of
secondary electrons primary electrons
emitted electrons photoelectrons
DC sputtering cannot be used for deposition of
Metal Alloy Oxide All above
Nanotubes usually form in bundles. Which is the best description of
such bundle?
The tubes are aligned, axes parallel, with van der Waals forces
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operating between adjacent tubes.
The tubes are connected together by covalent C-C bonds.
The tubes are randomly organized, with the axes of the tubes
lying in random directions
The bundles are of discrete sizes, and dipole-dipole forces hold
the tubes together
State True or False 06
The electron mobility in semiconductors can be greatly decreased
by the formation of polarons.
The SPR observed for insulator nanoparticles.
In AFM, the sample is mounted on a piezoelectric tube.
The ball milling is a top down method.
The Drude model neglects any long-range interaction between the
Electron and the ions or between the electrons.
The melting point of the nanoparticles is smaller than the bulk sized
particle.
Q.2 Write short notes:
Quantum confinement 05
Electroluminescence 04
Electrodeposition 04
Q.3 Describe the basic working principle of an STM and explain the charge
transfer in terms of LDOS
14
Q.4 Describe the basic working principle of a „metalic‟ SET. 14
Q.5 Derive the AC electrical conductivity of a metal according to Drude model.
Explain the inadequacies of Draude model and write the assumptions made
in Free Electron model.
14
Q.6 "Template-assisted synthesis is very efficient tool to grow highly
ordered and nano-wires/rods"- Explain.
10
Explain in Surface Plasmon resonance (SPR). 4
Q.7 "Bottom-up technique is more convenient for nano fabrication"
Explain
10
Why is spatial resolution of STM better than AFM? 4