About this previous year paper
Course: B.Tech (All Branches – Common Elective)
Subject Code: EOE042
Subject Title: Nano Sciences
Exam Type: Theory
Duration: 3 Hours
Maximum Marks: 100
SECTION – A (10 × 2 = 20 Marks)
Short and conceptual questions covering key definitions and phenomena in nanoscience
| No. | Term | Description |
|---|---|---|
| (a) | Nano Diamond | Carbon material with nanocrystalline diamond grains; exhibits extreme hardness, high thermal conductivity, and chemical stability. |
| (b) | Quantum Dots | Semiconductor nanocrystals exhibiting size-dependent optical and electronic properties due to quantum confinement. |
| (c) | Fullerenes | Allotropic carbon molecules (C₆₀, C₇₀, etc.) forming spherical cage-like structures — used in drug delivery, superconductors. |
| (d) | Luminescence | Emission of light by a substance not resulting from heat (includes fluorescence and phosphorescence). |
| (e) | Face-Centered Cubic (FCC) Nanoparticles | Crystalline structure with atoms at cube corners and face centers (e.g., Au, Ag, Ni). Stable and dense packing. |
| (f) | Lattice Vibrations | Oscillations of atoms about their equilibrium positions — quantized as phonons. |
| (g) | Excitons | Bound state of an electron and a hole attracted by Coulomb force in semiconductors. |
| (h) | Magic Numbers | Specific cluster sizes of atoms that are unusually stable due to closed electronic shells. |
| (i) | Fermi Surfaces | Surfaces in momentum space separating occupied from unoccupied electron states at absolute zero. |
| (j) | Trap Levels | Energy levels within the bandgap that trap charge carriers, influencing conductivity and luminescence. |
SECTION – B (5 × 10 = 50 Marks)
Conceptual and analytical questions covering synthesis, properties, and instrumentation of nanomaterials
(a) Carbon Nanotubes (CNTs)
Cylindrical carbon molecules (single or multi-walled).
Properties: High tensile strength, thermal conductivity, and electrical mobility.
Applications: Nanoelectronics, composite reinforcement, drug delivery.
(b) Quantum Dot Laser & Superconductivity
Quantum Dot Lasers: Operate via discrete energy levels; low threshold current and tunable wavelength.
Superconductivity: Nanostructures can enhance critical current and magnetic flux pinning.
(c) Electron–Material Interaction & Gold Coating in SEM
Electrons interact through elastic scattering, inelastic scattering, and secondary emission.
Gold Coating: Applied on non-conductive samples to prevent charging, improve signal, and enhance imaging in SEM (Scanning Electron Microscope).
(d) Atomic Force Microscopy (AFM)
Working Principle: Uses a cantilever with a sharp tip to scan the surface; deflections measured via a laser beam.
Applications: Surface topography, nanomechanical property measurement, and molecular imaging.
(e) Nanomaterial Growth Techniques
Chemical Vapor Deposition (CVD)
Sol–Gel Method
Physical Vapor Deposition (PVD)
Thermal Evaporation – Material evaporated under vacuum, condenses on cooler substrate forming thin films.
(f) Graphene
Single layer of carbon atoms arranged in a 2D honeycomb lattice.
Properties: High electrical conductivity, mechanical strength, transparency.
Applications: Flexible electronics, sensors, batteries, and quantum devices.
(g) Localized Particles & Trap States
Donors: Add free electrons to conduction band.
Acceptors: Create holes in valence band.
Deep Traps: Defects deep within bandgap that capture carriers for long durations — crucial in photodetectors and semiconductors.
(h) Raman Spectroscopy
Principle: Inelastic scattering of photons (Raman effect).
Measures vibrational modes of molecules.
Applications: Characterization of CNTs, graphene, thin films, and molecular identification.
SECTION – C (2 × 15 = 30 Marks)
Long derivation and theory-based questions
Q3. Time-Dependent Schrödinger Equation
Derivation from classical wave mechanics:
iℏ∂Ψ∂t=H^Ψ=[−ℏ22m∇2+V(x)]Ψi \hbar \frac{\partial \Psi}{\partial t} = \hat{H}\Psi = \left[-\frac{\hbar^2}{2m}\nabla^2 + V(x)\right]\Psiiℏ∂t∂Ψ=H^Ψ=[−2mℏ2∇2+V(x)]Ψ
Explains probability amplitude evolution of quantum particles — fundamental to nanophysics and quantum confinement.
Q4. Inert Gas & Superfluid Clusters
Inert Gas Clusters: Argon, neon — form van der Waals bonded clusters at low temperature.
Superfluid Clusters: Exhibit zero viscosity and quantum coherence — used to trap and cool nanoparticles for quantum simulations.
Q5. Transmission Electron Microscopy (TEM)
Working: Electron beam transmitted through ultra-thin specimen → image formed based on scattering contrast.
Advantages: High-resolution imaging (~0.1 nm), crystallographic and compositional analysis.
Applications: Nanoparticle morphology, crystal defects, and phase identification.
Summary
This Nano Sciences (EOE042) paper comprehensively tests:
| Topic Area | Concepts Covered |
|---|---|
| Nanomaterials | CNTs, fullerenes, quantum dots, graphene |
| Characterization Tools | AFM, SEM, TEM, Raman spectroscopy |
| Quantum & Solid-State Physics | Schrödinger equation, excitons, Fermi surfaces |
| Growth & Fabrication | CVD, PVD, thermal evaporation |
| Applications | Electronics, energy storage, medicine, and sensors |