Applications of UV-Vis Spectrometry: M+h excitation M relaxationM+h/heat How probable? ranges 0 to ~100,000 L/mol.cm "forbidden" "allowed" electronic transition Which electrons get excited? In UV-Vis.photon provides enough energy to move outer valence (bonding)electrons Organic molecules Ψo=ΨsA+ΨsB Bonding o molecular orbital Ψ。*=ΨsA-ΨsB Antibonding o molecular orbital Ψx=Ψpa+WPB Bondingπmolecular orbital x*=ΨpA-ΨpB Antibonding n molecular orbital (c)o*orbital (b)πorbital (dπ*orbital Fig 14-1 CEM 333 page 4.6 Applications of UV-Vis Spectrometry: M + hu excitation ¾ ¾ ¾ ¾ ¾ ® M * relaxation ¾ ¾ ¾ ¾ ¾ ® M + hu / heat How probable? e ranges 0 to ~100,000 L/mol·cm "forbidden" "allowed" electronic transition Which electrons get excited? In UV-Vis, photon provides enough energy to move outer valence (bonding) electrons Organic molecules ys = ysA + ysB Bonding s molecular orbital ys * = ysA - ysB Antibonding s * molecular orbital yp = ypA + ypB Bonding p molecular orbital yp * = ypA - ypB Antibonding p * molecular orbital Fig 14-1 CEM 333 page 4.6