Phase portrait and fractal analyses in nanobiophotonics: carbon nanoparticle aided intra-pigment energy transfer in leaves

Abstract

The paper delineates the potential application of nonlinear time series analysis (TSA) in Nanobiophotonics to explore the soot-assisted intra-pigment energy transport mechanism in leaves. The soot nanofluid, containing nano carbon allotropes, prepared in different concentrations, is sprayed over Lablab purpureus (L.) sweet leaves. The chlorophyll extracted from the leaves after ten days is subjected to UV-Visible absorption and single beam thermal lens (TL) studies. The variation of the absorbance of signature peaks of chlorophyll pigments with the soot concentration reveals the role of soot in the intra-pigment energy transport, divulged through the time series TL signal. The TSA of the TL signals, the plotting of phase portraits, and the computation of sample entropy (S), fractal dimension (FD), and Hurst exponent for the pigment-soot systems unwrap the particle/molecular dynamics and the flow of energy within the system. The analysis by segmenting the variations of the TSA measures with soot concentration reveals that the values of S and FD of the system are high in the low and high concentration ranges, in agreement with the randomness reflected in the phase portrait. The middle region, where S and FD decrease, seems more energy-efficient for the photosystem through heat trap and energy exchange between the pigment-soot system. The study gives information about the critical concentration range suitable for increased photosynthesis in leaves and yield enhancement.