M.Sc. (Semester IV) (CBCS) Examination Mar/Apr-2018
Physics (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 the Correct alternatives:
08
If the size of the metal nanoparticles decreases then the position of the SPR peak
shifts towards lower wavelength
shifts towards higher wavelength
remains same
none of the above
In bottom up approach the building blocks can be
atoms
molecules
clusters
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
If an electron is confined in limited space then the allowed energy states are
continuous
discrete
limited
none
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
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 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
Page 2 of 2
SLR-UN-489

State True or False Fill in the blanks:
06
The melting point of the nanoparticles is smaller than the bulk sized particle.
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 Drude model neglects any long-range interaction between the electron and the ions or between the electrons.
The SPR observed for insulator nanoparticles.
The ball milling is a top down method
Q.2
Write a short note on:
14
Polaron conduction mechanism
05
Quantum confinement
05
Molecular machines
04
Q.3
What is magnetron sputtering? Explain the basic difference between the magnetron sputtering and conventional sputtering.
10
"In principle, AFM resembles the record player as well as the stylus profilometer"-Explain
04
Q.4
Explain how endo-fullerenes can be used as one-dimensional metal-semiconductor junctions. Explain how a CNT can be bent to a ring.
14
Q.5
"Template- assisted synthesis is a very efficient tool to grow highly ordered and nano-wires/rods" Explain
10
Write a note on BN nanotubes
04
Q.6
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.7
Show that in STM the tunneling current varies exponentially as the tip-sample distance.
14