3 Quantification of excellent SERS sensitivity

The quantification of "excellent SERS sensitivity" can be determined by evaluating the enhancement factor (EF) achieved in a SERS experiment.

The enhancement factor is a measure of the amplification of the Raman signal obtained through SERS compared to traditional Raman spectroscopy. It is calculated by dividing the intensity of the Raman signal obtained from a molecule adsorbed on a SERS-active substrate by the intensity of the same molecule in bulk solution.

EF = (I_s / N_s) / (I_b / N_b)

Where:

• I_s is the intensity of the Raman signal obtained from the molecule adsorbed on the SERS-active substrate.
• N_s is the number of molecules contributing to the Raman signal on the substrate.
• I_b is the intensity of the Raman signal of the same molecule in bulk solution.
• N_b is the number of molecules contributing to the Raman signal in bulk solution.

A higher EF indicates a stronger enhancement of the Raman signal, therefore reflecting a higher SERS sensitivity. The exact value that qualifies as "excellent" SERS sensitivity may vary depending on the specific application and requirements. However, in general, an EF of at least 10^6 or higher is often considered excellent SERS sensitivity