New Mechanism of Extractive Electrospray Ionization Mass Spectrometry for Heterogeneous Solid Particles.

Real-time in situ mass spectrometry analysis of airborne particles is important in several applications, including exposure studies in ambient air, industrial settings, and assessing impacts on visibility and climate. However, obtaining molecular and 3D structural information is more challenging, especially for heterogeneous solid or semisolid particles. We report a study of extractive electrospray ionization mass spectrometry (EESI-MS) for the analysis of solid particles with an organic coating.

Simulations of photopumping in doubly illuminated liquid membranes containing photoactive carriers.

A steady-state model used to simulate photofacilitated active transport against a concentration gradient, called photopumping, is described. Central to this model is the idea that the carrier can be in either a strongly binding or a weakly binding form and light can be used to control the interconversion rate between the two forms. Most experimental and theoretical studies have focused on systems in which only one side of the membrane is illuminated at a time to form singly illuminated liquid membranes.

Simulations of photomodulated solute transport in doubly illuminated liquid membranes containing photoactive carriers.

A steady-state model describing photofacilitated transport in liquid membranes under double illumination is presented. The model allows for the exploration of the effects of a wide range of thermodynamic and kinetic carrier properties on the control of photoinduced transport rates of solutes, called photomodulation. Most previous experimental and theoretical studies have explored the illumination of only the feed or sweep side of the membrane, while this study examines the effects of illuminating both sides simultaneously.

Fabrication and use of nanometer-sized electrodes in electrochemistry.

Electrodes with electrochemical dimensions as small as 10 angstroms have been fabricated and used for electrochemical studies. These nanometer-scale electrodes have enabled the measurement of electron-transfer rate constants, k(het), that are two orders of magnitude faster than k(het) values accessible with any other electrochemical method.