“…The Raman bands at 515 and 519 cm −1 are attributed to the A 1g and B 1g vibrational modes and the peak at 634 cm −1 is assigned to the E g vibrational mode (Karunagaran et al, 2005). The peak at 555cm −1 is ascribed to the glass substrate (Djaoued et al, 2012;Daniel et al, 1987;Gotić et al, 2000;Cazzanelli et al, 1999b;Ohsaka et al, 1978;Balaji et al, 2009;Balachandran and Eror, 1982;Rezaee et al, 2011;Yazid et al, 2018;Alam and Cameron, 2002;Dinh et al, 2003;Judeinstein et al, 1992;Huang et al, 1997).…”