Mn(II) is of [d.sup.5] configuration which is high spin complex with doubly forbidden transition
. Tunabe-Sugano diagram shows that the Russell-Saunders term for [d.sup.5] high spin system is [sup.6]S with [sup.6][A.sub.1g] as the ground term symbol.
The energy band gap for indirect allowed and indirect forbidden transition
is decreased with the increase of the titanium oxide nanoparticles concentrations, this behavior attributed to creation of new levels in the band gap, lead to facilitate the crossing of electrons from the valence band to these local levels to the conduction band, consequently the conductivity increase and the band gap decreases , as shown in figure 4 and figure 5.
It even seems to be that the model applies for both, allowed and forbidden transitions
, however, this should be verified with further data; we have here only one forbidden transition
in our data set.
The LIF system consists of a Nd:YAG laser, a dye laser to produce 504.2 nm light to cause the forbidden transition
through Stark and quadrupole (QDP) transitions from 21S atoms to 31D states of HeI.
The energy band gap is calculated by the relation: [alpha]h[upsilon] = c[(h[upsilon] - [E.sub.g]).sup.r] where h[upsilon] is the photon energy, c is a constant, [E.sub.g] is the optical energy band gap, r=2, or 3 for indirect allowed and indirect forbidden transition
. The energy band gap of the (PVA-PAA-PVP-MgO) nanocomposites decreases with increasing of the magnesium oxide nanoparticles weight percentages which related to the increase of the local level in forbidden energy gap.