Abstract Title: Multifractal detrended fluctuation analysis of photon intensity series in nano-structured porous media: A single molecule study
Abstract Submitted to: MINERAL AND ROCK PHYSICS
Abstract Text:
Understanding the mechanisms of transport in nano-structured shales at the molecule level helps exploration and production of unconventional reservoirs at large scales. In this study, we conducted single molecule fluorescence fluctuation experiments to uncover the complex dynamics behind molecular transport in nanoporous media. Specifically, a confocal fluorescence microscope was employed to acquire single-molecule photon intensity time series in three porous anodic aluminum oxide (AAO) membranes comprised of pores with 5, 10, and 20 nm diameters and each with porosities ranged between 10 and 15%, similar to shales. The pores were filled with Nile red dye at 10 nanomolar concentration in toluene solution. The multifractal detrended fluctuation analysis (MF-DFA) from statistical physics was then employed to analyze the photon intensity time series data and to compare results from bulk solution with those obtained in the pores. Photon intensity time series were obtained using three bin times; 0.1, 1, and 10 ms. By applying the MF-DFA to obtain the generalized Hurst exponent, h(q), we found h(q) near 0.5 in solution while in pores h(q) > 0.5, showing persistence and correlation in the intensity time series. We also found similar results and weak multifractality for the 0.1 and 1 ms bin times for different membranes, while strong multifractality was observed for the 10 ms bin time. The results also showed that the intensity distribution deviated from the Poisson probability density function for the 10 ms bin time. This is probably due to absorption and desorption of dye molecules from the pore surface that was better captured using longer bin times.
Luqman OLAWALE
Description
Funded by:
Current Institute of Study/Organization: Kansas State University
Currently Pursuing: Master's
Country: US