A solid in bulk has a band gap corresponding to the optical absorption edge of 475 nm. what will happen to the absorption edge when the solid is made as nanopar

mam option d ans is given

In the bulk matter, the bands are actually formed by the merger of bunch of adjacent energy levels of a LARGE number of atoms and molecules.As the particle size reaches the nano scale, where every particle is made up only a VERY SMALL number of atoms or molecules, the number of overlapping of orbitals or energy level decreases and the WIDTH OF THE BAND GETS NARROWER. This will cause an INCREASE IN ENERGY GAP BETWEEN THE VALENCE BAND AND THE CONDUCTION BAND

when energy gab increases btw the valence band and conduction band then what is the role of absorption here mam??

See lower wavelength has higher energy

Since energy gap is increased so it will absorb now shorter wavelength

Got Shristy

ok mam got it

yes sir.... explanation ?

when the size is considereable as nano particles the band gap increases....so there is large gap between VB and CB due to this conductivity decreases...so absorption shifts towards shorter wavelength

Means more forbidden region is created so more restrictions on movement of electrons...so conductivity gets decreases

got it shristy??

absorption shift towards shorter wavelength ?????ye smjh ni aaya sir ye kaise hoga ?

conductivity kam hoga na iss wajah se...absorption kam ho jayega large energy gap ke wajah se means shift towards shorter wavelength

now got shristy??