Measurement of the Raman Line Widths of Neat Benzenethiol and a Self-Assembled Monolayer (SAM) of Benzenethiol on a Silver-Coated Surface-Enhanced Raman Scattering (SERS) Substrate

Raman line widths of neat benzenethiol and a self-assembled monolayer (SAM) of benzenethiol on a surface-enhanced Raman scattering (SERS) substrate have been measured using a mini spectrometer with a resolution (full width at half-maximum) of 3.3 ± 0.2 cm⁻¹. Values of 7.3 ± 0.7, 4.6 ± 0.6, 2.4 ± 0.6, 3.2 ± 0.5, 8.8 ± 0.9, and 11.0 ± 1.1 cm⁻¹ have been determined for the Raman line widths of the 414, 700, 1001, 1026, 1093, and 1584 cm⁻¹ modes of neat benzenethiol. Values of 13.3 ± 0.7, 9.1 ± 0.7, 5.1 ± 0.6, 5.9 ± 0.6, 13.3 ± 0.5, and 8.7 ± 0.5 cm⁻¹ have been determined for the SERS line widths of a benzenethiol SAM on a silver-coated SERS substrate for the corresponding frequency-shifted modes at 420, 691, 1000, 1023, 1072, and 1574 cm⁻¹. The line widths for the SERS modes at 420, 691, 1000, 1023, and 1072 cm⁻¹ are about a factor of two larger than those of the corresponding Raman modes. However, the line width of the SERS mode at 1574 cm⁻¹ is slightly smaller than the corresponding Raman mode at 1584 cm⁻¹.