Increase in PL intensity with doping concentration observed for solutions (Fig ). Excess carrier generation causes higher luminescence. However, it should be understood that the sample was in solution state and therefore the ion interactions with increase in doping as mentioned previously in XRD studies will not be effective in this case. The increase in PL intensity with increase in Mn doping was simply due to the fact that more ions were available with increase in doping. There was decrease in intensity with increase in Mn doping from 1% to 3% as Mn ions interacted more with the NiO crystallites and defects. As the self-interaction between the Mn ions increased with increase in Mn concentration to 5% and fraction of Mn ions -Lattice interaction decreased, the PL intensity showed a rise. The PL spectra for the solid samples showed However, two absorption peaks around 300 and 400 nm were observed. The higher wavelength peak got reduced in intensity with increase in doping. The two absorption edges obtained in case of Mn-NiO have two explanations. The first one is the change in particle shape. If the particles are rod shaped, there will be two modes of electronic oscillations caused by the electric field of the light. One of the modes called the longitudinal modes will cause oscillations along the length of the particle and the other will cause oscillation perpendicular to it (Transverse mode). The transverse mode usually occurs at lower wavelength which in this case is around 300 nm. The longitudinal mode on the other hand is observed at 400 nm. From the Fig it can also be seen that the intensity of the absorption peak for the longitudinal mode decrease with increase in Mn doping. Hence the particles are becoming more spherical in nature which is also beneficial for magnetic applications .