Introduction to nanoscience & nanotechnology

Introduction to nanoscience & nanotechnology

1. What They Are

• Nanoscience = study of phenomena and manipulation at nanoscale ($1$–$100$ nm), where properties differ from bulk due to surface effects and quantum confinement.
• Nanotechnology = engineering at nanoscale: designing, synthesizing, and applying nanomaterials and nanodevices to exploit those new properties.

$1$ nm = $10^{-9}$ m = 10 atoms (~0.3 nm per atom). Virus ~100 nm, transistor gate now ~3 nm (nano).

2. Why Nanoscale Is Special (preview)

At $1$–$100$ nm:

• Surface-to-volume ratio explodes ($∝1/r$) ⇒ reactivity, catalysis.
• Quantum confinement when size comparable to de Broglie / exciton Bohr radius ⇒ band gap and optical/electrical properties become size-tunable.
• Dominance of surface: many atoms on surface → different mechanics, melting point, magnetism.

3. Fabrication Approaches

Approach	Idea	Example
Top-down	Bulk → smaller (etch, lithography, milling)	Photolithography for ICs, ball milling
Bottom-up	Atoms → larger (self-assembly, chemical synthesis)	CVD, sol-gel, colloidal synthesis of quantum dots

Characterization: TEM, SEM, AFM, STM, XRD (next topics).

4. Interdisciplinary Nature

Nanoscience spans physics (quantum), chemistry (synthesis), biology (drug delivery), engineering (devices), materials.

5. Exam Points

• Define nanoscience vs nanotechnology and $1$–$100$ nm range — 3-5 marks, very frequent.
• Mention top-down vs bottom-up — 5 marks, frequent.
• Give size comparison (atom 0.3 nm, virus 100 nm) — 3 marks.