M.Sc. (Semester IV) (CBCS) Examination Nov/Dec-2018
(Materials Science)
PHYSICS OF NANO MATERIALS
Time: 2½ Hours Max. Marks: 70
Instructions: Q 1 and Q 2 are compulsory.
Attempt any three questions from Q. 3 to 7.
All questions carry equal marks.
Q.1 Choose correct alternatives. 08
If the size of the metal nanoparticles decrease then the position of the
SPR peak exhibits.
Blue shift Red shift
No shfit None of the above
DC sputtering cannot be used for deposition of
Metal Alloy
Oxide All above
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
Nanotubes usually form in bundles, which is the best description of such
a bundle?
The tubes are aligned, axes parallel, with van der Waals forces
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.
The surface area to volume ratio of a sphere with radius 30 nm is
108 109
107 106
In SEM the morphology of the sample is achieved with the help of
secondary electrons primary electrons
emitted electrons photoelectrons
In bottom up approach the building blocks can be
atoms molecules
clusters all above
If an electron is confined in limited space then the allowed energy states
are
continuous discrete
limited none
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SLR-VN-391
State True or False/ Fill in the blanks. 06
The ball milling is a top down method.
The melting point of the nanoparticles is smaller than the bulk sized
particle.
The Drude model neglects any long-range interaction between the
electron and the ions or between the electrons.
In AFM, the sample is mounted on a piezoelectric tube.
The electron mobility in semiconductors can be greatly decreased by the
formation of polarons.
The SPR observed for insulator nanopaticles.
Q.2 Write a short note on:
Quantum confinement 05
Electroluminescence 05
Molecular machines 04
Q.3 Derive the AC electrical conductivity of a metal according to Drude model. Explain
the inadequacies of Drude model and write the assumptions made in Free
Electron model.
14
Q.4 Describe the basic working principle of a „metallic‟ SET. 14
Q.5 "Template- assisted synthesis is a very efficient tool to grow highly ordered
and nano-wires/rods" explain.
10
Explain in brief the basic process of VLS techniques. 04
Q.6 "Bottom-up techniques is more convenient for nano fabrication" Explain. 10
Why is spatial resolution of STM better than AFM? 04
Q.7 Describe the basic working principle of an STM and explain the charge transfer in
terms of LDOS.