Moringa oleifera Leaf Extract-Mediated Green Synthesis of Nanostructured Alkaline Earth Oxide (MgO) and Its Physicochemical Properties

Table 3

Photoluminescence emission spectra at different temperatures of MgO nanoparticles.

Metal oxide NPs	Peak position wavelength (observed in nm)	Emission	Energy (eV)	Attribution	References
MgO nanoparticles	359	UV	3.45	Surface defects	[31, 74]
	378	Violet	3.2	Defect band transition. F^+ (or ) centers	[31, 33, 54, 55, 75]
	411		3.01
	413		3
	438		2.83
	491	Blue	2.52	Recombination of electrons with oxygen vacancies	[31, 33, 34, 75]
	518	Green	2.39	Oxygen vacancies (Vo)	[31, 33, 48, 52, 53, 74, 76]
	538	Green	2.30
	593	Orange	2	Relaxation luminescence of defect centers F2^1+created by mechanical stress	[31, 48, 52, 53, 74, 76]