Enhanced Raman Scattering of Nitroexplosives on Metal Oxides and Ag/TiO₂ Nanoparticles

Detection and identification of explosives by surface enhanced Raman scattering

“…Sc2O3 was also tested and the results were quite similar to TiO2 concluding that the spectra obtained by using oxides to enhance the Raman signal are quite different from ordinary SERS since all vibrations seem to be enhanced by the same factor [45]. In addition, the authors postulated that enhancement depends on the physical form of the oxide: type of polymorph present; bulk, cluster, or nanoparticle present; and oxidation state of the metal cation [45,48].…”

“…Besides Au and Ag nanoparticles, other compounds have been explored as SERS substrates either on its own or in combination with Au/AgNPs, such as titanium dioxide [43][44][45][46][47][48], silver vanadate and copper [49], silver molybdate [33], alumina [50,51], nickel [52], graphite (single-wall carbon nanotubes) [53], silicon [54], graphene [41,55],…”

“…were deeply studied by Cruz-Montoya et al for nitroexplosives SERS detection, mainly TNT and DNT [43][44][45][46][47][48]. As a summary of all their work, the more relevant results are displayed below.…”

“…TiO2 was compared with Ag/Au alloys for TNT detection being Ag/Au alloys with which TNT signal enhanced best [45]. Later studies in which Ag, Au, Ag/Au, and Ag/TiO2 NPs were compared for TNT detection, the order of NPs in terms of highest EF was the following: Ag > Ag/Au > Ag/TiO2 > Au [47,48]. By using Ag NPs, a LOD of 10 -12 M, corresponding to 0.1 fg, was achieved for TNT.…”

Detection of Explosives by SERS Platform Using Metal Nanogap Substrates

“…If a nitro group is attached to an aromatic ring as in TNT, this vibrational mode shifts to a slightly lower frequency [ 27 ]. In the case of TNT molecules, the reported frequencies of NO 2 symmetric stretching modes vary between 1330 and 1380 cm −1 in the literature [ 28 , 29 , 30 , 31 , 32 ], and the spectral shapes appear to be different from one another, which are not currently well understood.…”