Surface-Enhanced Raman scattering of methylene blue on titanium nitride nanoparticles synthesized by laser ablation in organic solvents.

Suspensions of titanium nitride (TiN) nanoparticles (NPs) were prepared using nanosecond Ce:Nd:YAG pulsed laser ablation (λ = 1064 nm) of a TiN target immersed in various solvents such as Toluene (C6H5CH3), Acetonitrile (CH3CN), and N, N-dimethylformamide (C3H7NO). The synthesized NPs were characterized by applying a range of spectroscopic, structural, and compositional analysis techniques. The obtained TiN NPs in N, N-dimethylformamide (DMF-TiN NPs) solvent showed strong optical absorption in the near-infrared (NIR) range; Whereas, the obtained TiN NPs in toluene (T-TiN NPs) and acetonitrile (AN-TiN NPs) solvents were covered with a carbon matrix layer that quenched their surface plasmon resonance (SPR). The carbon matrix on the NPs was removed by thermal oxidation to obtain carbon-free TiN NPs. All the prepared carbon-free TiN NPs were employed as substrates for the surface-enhanced Raman scattering (SERS) spectroscopy of methylene blue (MB) molecules as a probe molecule adsorbed on the surface. All substrates indicated nearly the same order of enhancement factors (EFs) (~103) for MB.