Table 1. Vibrational modes of MB corresponding to its Raman spectrum.

MB (cm-1)	MB + AuNPs-1(cm-1)	MB + AuNPs-2(cm-1)	MB + AuNPs-3(cm-1)	Reported results (cm-1)	Peak assignment
451	450	447	447	480a 445b 449c	δ(C-N-C), δ(C-S-C)
504	503	482	483	497b502c	δ(C-N-C)
-	599	597	605	613a	δ(C-N-C)
683	673	671	675	677b 688c	γ(C-H)
774	774	774	773	769c	δ(C-N-C), δ(C-S-C), ν(N-CH3)
-	893	895	902	-	-
1011	1042	1039	1034	1032a 1036b 1003c	β(C-H)
1160	1159	1154	1154	1123a 1181b	γ(C-H) ν(C-N)
1335	1329	1299	-	1396b	α(C-H)
1402	1397	1386	1391	1413d	νasym(C-N)
1505	1504	1501	-	1512e	δasym (C-C-C)
1626	1626	1623	1626	1618b 1617d	ν (C-C) ring

Shown are Raman shifts (in cm^-1) of methylene blue on the different gold NP samples compared to reported data. AuNPs-1: Different shaped nanoparticles of a broad size range (10 to 200 nm). AuNPs-2: Quasi-spherical nanoparticles with some triangular shapes in a main size range of 6 to 23 nm. AuNPs-3: Small, quasi-spherical nanoparticles (3 to 12 nm). Abbreviations: α, in-plane ring deformation; β, in-plane bending; γ, out-of-plane bending; δ, skeletal deformation; and ν, stretching.

^a Ref[35].

^b Ref[36].

^c Ref[37].

^d Ref[38].

^e Ref[39].