Synopsis of Sponsored Research

Our main research focus has been and is in applying atomic emission and mass spectroscopic measurements for elemental and isotopic analysis using high-temperature plasmas such as the inductively coupled plasma (ICP). The field of ICP spectrometry has revolutionized simultaneous elemental determinations at the ultratrace, trace, minor, and major constituent levels for the quantitative determination of the elemental composition of various materials, thus providing answers to a number of basic questions of universal importance. What trace amounts of undesirable substances are in the water, orange juice, coffee, tea, or the wine you drink?  How much and which toxic elements are being emitted into the air by a nearby coal or nuclear utility plant?  What trace substances are on a victim's clothes or a pair of gloves left at the crime scene, which might identify the murderer? What levels of trace impurities affect the physical, mechanical, optical, and electrical properties of materials important in the manufacture and performance of semiconductor devices such as a computer chip? 

Specifically, our group investigates and develops new sample introduction systems, new high-temperature plasmas, novel diagnostic techniques, and fresh methodologies for mathematical modeling of nebulization systems and plasmas to advance reliable elemental, speciation, and isotopic analysis of gases, solutions and solids easily, rapidly, with minimal sample consumption and at low cost. These devices, approaches, and techniques offer promise of solving singularly difficult analytical problems that either exist now or are likely to arise in the future in diverse fields such as energy generation and consumption, materials science, semiconductor development and product designs, pharmacology, toxicology, biomedicine, nutrition, geochemical and petroleum prospecting, industrial processing, environmental monitoring, and nuclear monitoring and forensics. In conducting our research, we often combine forces with an extensive array of prominent scientists in academia and federal and industrial laboratories worldwide, both in chemistry and other fields. Emphasis is placed on:

1. Development and exploration of direct solution introduction nebulizers for analytical spectrometry with high-temperature plasmas;

2. Development and characterization of low-cost sample introduction systems that consume microliter or microgram quantities of samples that are expensive, toxic, hazardous, or limited in quantity;

3. Investigation of micro- and nanonebulizers that generate a fine, uniform-velocity, monodisperse aerosol for microbore chromatography and capillary electrophoresis;

4. Fundamental studies through computer modeling (with Professor Deborah A. Levin, Department of Aerospace Engineering, Pennsylvania State University) to unravel the destiny of droplets in plasmas, on a spatially- and temporally-resolved basis, to ultimately provide distinctive and remarkable information that has not been yet predicted or measured for direct liquid introduction spectrometries;

5. Investigation of innovative spray characterization techniques, based on optical patternation, to allow the rapid elucidation of spray structure, droplet mass distribution, and spatial droplet size distributions;

6.   Investigation of dual-beam, light-scattering interferometry for simultaneous measurements of droplet-size and velocity distributions of aerosols from various nebulizers, and for time-resolved studies of droplets;

7.   Exploration of electrical mobility-based techniques for measuring particle size distribution in the range of 10 to 1,000 nm;

8.  Generation and fundamental investigation of helium inductively coupled plasmas (He ICP) that are suitable for the excitation/ionization of high-energy spectral lines and difficult-to-ionize elements, to enhance the detecting power of a number of elements and to minimize spectral interferences;

9.   Development of versatile plasma matching networks for the generation and analytical and fundamental investigations of discharges in various gases.

10. Development of computer algorithms and spectral line profiles data bases (with Dr. Chantal Stehlé, Laboratoire de l'Univers et de ses Théories, Observatoire de Paris) for the calculation of electron number density and fundamental properties of plasmas;

11. Mathematical modeling and computer simulation for predicting fundamental properties of helium ICP discharges (with Professor J. Mostaghimi, Department of Mechanical Engineering, University of Toronto); computer modeling of mixed-gas discharges to predict the behavior of plasmas on a fundamental basis

12.  Investigation of glow discharges for direct analysis of nonconductive samples.

In addition, in the area of forensic studies, the utility of infrared microscopy for the identification of single fibers is examined to prepare a computer-based spectral library of fibers for forensic studies. The technique of Ar ICP mass spectrometry is applied to analysis of minute quantity of forensic samples and the development of fresh methodologies applicable to pharmaceutical industries. Investigation addresses fundamental principles behind the measurements, evaluation of the analytical potentials of the devices developed, and demonstration of the analytical methods in representative samples.

© 2007 Montaser Research Group. The George Washington University.