Alan Mark Schilowitz

Solvatochromism of Nile Red in Nonpolar Solvents

The absorbance and fluorescence spectra of Nile Red (NR) were examined in a series of nonpolar solvents comprising linear alkanes and a range of poly alpha olefins (PAO). These solvents span a 1000-fold range in viscosity and possess very similar dielectric constants and refractive index properties. A high-energy double peak with vibronic structure is observed in both fluorescence and absorbance spectra, possibly indicating that a locally excited (LE) state is accessed in these solvents. In addition, a red shift in peak position is observed with increasing refractive index; however, it is unaccompanied by any changes in Stokes shift. This shift is attributed to changes in the high-frequency polarizability of the solvent, which is a function of the refractive index. Finally, an increase in quantum yield with viscosity is also observed.

Applications of optical fiber sensors in the oil refining and petrochemical industries

Optical fiber distributed sensing technologies, consisting of many sensors in one single fiber, present unique and cost-effective solutions for the oil refining and petrochemical industries to optimize process operations and improve reliability and safety. In addition, optical fiber sensors do not require electrical power at the sensing locations, reducing the need for explosion-proof electronic packaging. This paper reviews state-of-the-art commercial optical fiber distributed temperature and strain sensing technologies, and presents challenges and opportunities for these technologies in the oil refining and petrochemical industries. Attention is drawn to the fundamental understanding of optical fiber materials and development of reliable sensor protection and installation methods for harsh environments.

Microcantilever sensors applications in the petroleum industry

Sensing applications in the petroleum industry pose unique challenges due to high viscosity and high refractive index of hydrocarbon fluids, which render many fluid-based techniques impractical. Real-time observation of adsorption, desorption, and competitive adsorption processes of long chain functionalized hydrocarbons onto activated cantilevers in static mode are shown. In addition, microcantilevers in dynamic mode are demonstrated to sense corrosion of very small (10ml) samples in fast (10 minutes) timescales.

Frequency Response of Microcantilevers in Viscous Fluids

This paper presents a new, general reconstruction algorithm that enables modeling of the experimental resonance spectrum of a prismatic microcantilever in a viscous fluid. A closed-form solution is obtained for the microcantilever frequency response from the equation of motion with fluid damping and internal friction terms, which allows direct calculation of the fluid damping and internal friction damping constants. In principle, the fluid damping constant has a simple relationship to viscosity thus potentially simplifying the process of obtaining viscosity from experimental data. Finally, the model is compared to experimental data.

Nanoscale Imaging of 3D Surfaces and Interfaces

Nanoscale characterization of a number of different properties of surfaces and interfaces includes topography, electrostatic and magnetic fields, material properties, tribological properties, piezoresponse, and surface potential. All these properties can be studied in flexible environments with minimal sample preparation and in ambient and liquid environments using scanning probe microscopy. This chapter will focus on two primary techniques: scanning tunneling microscopy and atomic force microscopy. These modalities allow a surface scientist to characterize and study surfaces, interfaces, and surface reactions.