Are morphologies of SERS active substrates multifractals? An in‐depth study from multifractal detrended fluctuation analysis

Abstract

This paper reports the first evidence that depicts multifractal nature of two different surface enhanced Raman scattering (SERS) active substrates of classes I and II, so fabricated from Langmuir–Blodgett and self‐assembly techniques. Multifractal detrended fluctuation analysis (MF‐DFA) has been performed from the field emission scanning electron microscopy and atomic force microscopy images of both the as fabricated SERS active substrates. Dependences of h()q on “q” together with the nonlinear variations of the classical scaling exponent []τ()q with “q” primarily reveal the multifractal nature of both the substrates. The singularity spectra for both the substrates of classes I and II exhibit bell‐shaped curves with finite spectral widths (W). Furthermore, the correlation coefficients (γ) and asymmetry indices (B) for the substrates have also been estimated from MF‐DFA. From these studies, we believe that multifractality may be considered as the hallmark of SERS active substrates, which to the best of our knowledge has been distinctively unveiled for the first time.