Module A-4 Molecular Electronics

Bohr Atomic Model

Hydrogen Emission Spectra

Principal Quantum Number

Principal Quantum Numbers

Orbital Quantum Number

l = 0 to l = (n–1)

Quantum Energy States

Principal Quantum Numbers

Molecular Orbital Considerations

H H-H H-H-H H-H-H-H (1s electrons)

Li Li-Li Li-Li-Li Li-Li-Li-Li (2s electrons)

(Li–Li = 2.67 A, H–H = 0.75 A)

Molecular -Bonding and * Bonding States

bonds• Electrons in chemical bonds ( e.g. H-H and C-H Electrons in chemical bonds ( e.g. H-H and C-H bonds) are generally quite localized and non-bonds) are generally quite localized and non-conducting. These bonds are conducting. These bonds are bonds. bonds.

Alkyl Chains and Aliphatic molecular Insulators

type orbits lie in type orbits lie in

the molecular plane the molecular plane

and are insulatingand are insulating

Formulation of Large Molecular Chains

Formation of Energy Bands from Constituent Atoms

Energy Bands for metals, semiconductors and Insulators

Bandgap vs. Chain Length

Poly(thiophene)

Saturation Effect

All properties approach a saturation value.

Bandgap vs. conjugation length

Increased conjugation length smaller bandgap

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Single Electron Transistors

Molecular Break junction SET

STM in Molecular Electronic Research

Semiconducting