( ( If ( initially ( ( the ( free electron ) ) ( was ( ( generated ( by ( ( some ( light incident ) ) ( on ( the material ) ) ) ) ) then ) ) ) ) ) ( ( the process ) ( ( is ( called ( luminescence ( induced ( by ( ( light or ) photoluminescence ) ) ) ) ) ) . ) ) )
(ROOT (S (SBAR (IN If) (S (ADVP (RB initially)) (NP (DT the) (JJ free) (NN electron)) (VP (VBD was) (VP (VBN generated) (PP (IN by) (NP (NP (DT some) (JJ light) (NN incident)) (PP (IN on) (NP (DT the) (NN material))))) (ADVP (RB then)))))) (NP (DT the) (NN process)) (VP (VBZ is) (VP (VBN called) (NP (NP (NN luminescence)) (VP (VBN induced) (PP (IN by) (NP (NN light) (CC or) (NN photoluminescence))))))) (. .)))
If initially the free electron was generated by some light incident on the material then the process is called luminescence induced by light or photoluminescence.
(ROOT (S (NP (NP (NNP Producing) (NN light)) (PP (IN without) (NP (DT a) (JJ high) (NN temperature)))) (VP (VBZ is) (VP (VBN called) (S (ADJP (JJ luminescence))))) (. .)))