It could be a charge transfer band or an aggregate band (H-aggregate or J-aggregate).
There is no quantum confinement in non-covalent molecular association.
Thanks you sir for your response,
Dear sir, does quantum confinement related to definite energy levels, which separates them from bulk ? If yes, can we term homo to lumo kind of charge transfer between two molecules as consequence of quantum confinement? V. N. Ravi Kishore V.
Quantum confinement is a term which derives from solid state physics, when the extent of the physical system becomes less than that of the bulk wavefunctions.
The physics of molecular systems should not be defined in such terms, but rather in terms of molecular orbitals, in which all electronic interactions are taken into account, a priori. Intermolecular interactions can either give rise to aggregation induced perturbation of the molecular orbital states, or new intermolecular charge transfer states.
Prabhjot Singh No. They could be donor levels, acceptor levels, trap states etc.
Thank you Hugh J Byrne and V. N. Ravi Kishore V.
Dear Sir,
Elaborating the question, as we know wavefunction ( where wave nature of matter persists) , can be ascribed to single fundamental particles (electron etc), atoms and molecules, thus, can we express nature of set of four molecules assembled via non covalent force as a wavefunction (that may be complicated one). If yes, then can we also describe this state (this four molecular state if devoid of any other external interaction, i.e. completely isolated) as a quantum state which has its own wavefunctions or quantum confined state?
A simple system to understand quantum confinement is particle in a box.
A free electron can possess any energy but when the same electron is put in a 1-D box then it cannot possess all possible energies but only certain energies. To put it differently the electron on confinement can occupy only certain discrete states.
Also as the dimensions of the box decrease, the gap between the levels increases.
In an atom, the electronic orbitals are described by atomic orbital theory, and are (quantum) confined to the atom by the intra-atomic forces.
In a molecule, the electrons experience interatomic forces, and the atomic states converge to molecular states, which are fully described by molecular orbital (quantum) theory.
If molecules come together in a gas or a crystal, the intermolecular forces should be considered. If the state of the system is still predominantly molecular, then it is still defined by (quantum) molecular states, which have been perturbed to a greater or lesser extent by the intermolecular interactions. Usually these are pi- bonding or hydrogen bonding interactions, which are not strong enough to substantially change the fundamental unit of the molecule (eg benzene, naphthalene crystals) and the molecular electronic states remain (quantum) confined to the molecule.
If the intermolecular interactions are strong enough that the state of the system is no longer dominated by the molecular orbitals, then it is not referred to any longer as a molecular system, and the band theory approximations of solid state physics apply,
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