University of Delhi 2010-2nd Year M.Tech Information Technology 1st nd synthesis and characterization of nanomaterials UNIVERSITY - Question Paper

This question paper contains 3 printed pages.

6994    Your Roll No

M.Tech. / II Sem.    j

NANOSCIENCE AND NANOTECHNOLOGY Paper NSNT-204 Synthesis and Characterization of Nanomatenals

3 hours    Maximum Marks 38

(Wnte: your Roll No on the tap immediately on receipt of this question paper}

Question No J n compulsory Answer any four from the remaining questions

1 Answer an> five questions, Each question carries 2 marks

(a)    How does the electron gun ised ip a Scanning election imciosrope (ShM) and transmission election nhcioscope (TEM) pioauce a oeam of monochromatic electrons⁰ How is the filament ciurent related to the beam cun enP

(b)    How do you measure the barrier height using a scanning tunneling microscope?

(c)    Draw an analogy between layered solids and giaphite What is graphene⁷

(d)    Preparation of cobalt aiummate from CoO and Al₂Oi requires a reaction temperature of 1200C. How could the reaction temperature be lowered?

(e)    Diamond and indium antimonide (InSb) aie both insulators, with band gaps (between the highest energy filled band and lowest energy empty band) of

5 5 eV and 0.15 eV respectively Are both materials transparent to visible light P

(f)    Show that the spacing of (hkl) planes in real space is connected with the hkl reciprocal lattice vector length by d_hk) - 2Tr/jQ_hki(    5x2-10

2 (a) The powder X-ray diffraction pattern of LSrH₃ shows the following reflections 20 = 23 25, 40.84, 47.53. 53 56, 69 49, 74 38 Index the data, determine the lattice type and lattice parameters

z

(b) How are the bright field and the dark field images recorded usmg the transmitted and the diffracted electrons in a transmission electron microscope⁰

7

3(a) Explain in detail the methods of preparing porous solids citing suitable examples

(5 marks)

(b) What are the different manipulation modes of STM to manipulate adatoms for nanolithography

(2 marks)

4 (a) How die Cdibon nanotubes synthesized⁷

(b) What aie the different imaging modes in an atomic force microscope (AFM)⁷ Identify the region of operation for the different modes usmg a force - distance curve

1

"> (a) What ait Phase iranfei catal\sts Discuss tlieti role in nano particles synthesis

(? marks)

(b) Metals damp intensity of light in a short distance Using the following electromagnetic wave equation, establish the relation between the damping (*)

constant and the dielectric constant (t(vv)

\

2 d²E* d²Er O dEr _=f __ ₊ .

dz² dr dt

where Fit ts the x component of elcctric field strength, t is the dielectric constant, o is the ac conductivity and E₀ is permittivity of empty space    7

6 (a) What are structure directing agents (SDA)^?

(b) Give examples of cationic and anionic surfactants

(2 marks)

(c) What are the effects (both elastic and inelastic) produced by electron bombardment on a thin specimen⁷ Use a schematic diagram to show the interaction volume for various electron specimen interactions.

(3 marks)

Attachment: university-of-delhi-2010-m-tech-information-technology-35315-1.pdf

Earning:   Approval pending.