Validation of SERS enhancement factor measurements.

Abstract: The huge signal enhancement that motivates the rapid spreading of surface‐enhanced Raman scattering (SERS) in a wide range of applications is commonly quantified by measuring the enhancement factor (EF). Concerning this important parameter, in this paper, we tackle 2 points: (a) We validate the use of a Macro Raman configuration with line focus to measure the EFs, against the more common Micro Raman one. The validation is carried out by comparing the EFs measured in the 2 configurations with the well‐established methodology, on the same set of commercial substrates. Macro Raman with line focus can be advantageous over the Micro Raman because it can provide a higher signal‐to‐noise ratio at equal laser intensity impinging on the sample (useful in sensing or analytical applications). (b) It is a common practice for practitioners validating an experiment by measuring a commercial compound, acting as a “standard,” whose properties have been already determined in the literature: To our knowledge, an equivalent “standard” does not exist for EF measurements, probably due to the reproducibility and aging issues that prevent them from being identically reproduced in different laboratories. Because the EF is the cross‐section ratio of a test molecule under SERS and normal Raman conditions, if one replaces the SERS substrate and the reference liquid with 2 commercial materials in the EF measurement procedure, this leads to the determination of another cross‐section ratio: We propose then to use the cross‐section ratio of suitable commercial materials for the validation of the instrumental procedure used to measure EFs. [ABSTRACT FROM AUTHOR]