个人简介

Education B.S., 1975, Eastern Michigan University Ph.D., 1978, University of Utah Postdoctoral, 1978-80, NBS (NIST)

研究领域

Analytical Chemistry

Research performed in this laboratory applies novel infrared and visible wavelength laser-based spectroscopic and optical processing techniques to molecular chemical analysis. Laser light sources are advantageous in spectrochemical analysis due to their high spectral radiance and their high temporal and spatial coherence. The inherent sensitivity limitation of conventional infrared absorption spectroscopy is being overcome using infrared laser light sources. Pulsed infrared lasers are used to excite gas-phase analyte species such as the new class of compounds called the alternative fluorocarbons. Sample absorbance is not monitored with infrared detectors. Instead, the perturbation to the sample matrix resulting from the absorbed energy is monitored by observing a change in the beam propagation of a visible probe laser. This technique, called pulsed laser photothermal spectroscopy, surpasses the conventional infrared absorption by reducing the low signal to background luminescence ratio and the use of a infrared detector. A variety of pulsed laser excited photothermal spectroscopy detection schemes are tested in this research. The ultimate goal is to obtain large signal magnitudes while reducing the shot noise limited background signal. The latter limits absorption spectroscopy and background reduction accounts for the inherent sensitivity of emission spectroscopy. Reduction of the probe laser background for pulsed laser infrared photothermal spectroscopy requires the development of high contrast probe laser radiance detection. Present and future research will be towards this goal. In particular, we are working on the development of an adaptable spatial filter for probe laser beam limiting. Using the limiter, infrared transitions of less than .0001 absorbance units can be observed with visible probe laser contrasts greater than 300. Optimum signal recovery is necessary to realize the advantages of pulsed laser spectrochemical techniques. The research also involves design and application of digital signal processing schemes for optimal pulsed signal recovery. Signals obtained in pulsed laser spectroscopy require specialized processing for efficient recovery and facile analytical interpretation. These signals are of high bandwidth, cyclic, and are typically dominated by non-white shot noise. We have found that adaptive matched filter signal processing techniques can be optimal for rapid linear pulsed signal analysis. Work in this area has recently been extended to include the case of non-linear signals observed in many pulsed laser excited spectroscopic experiments and to account for the limiting shot noise statistics of optical detection. In related research, optical signal processing techniques are being applied for time and wavelength dependent spectroscopic signal analysis. The intrinsic speed and parallel structure of incoherent optical processing schemes are ideally suited to problems involving the analysis of complex mixtures. Optical processing of spectroscopic signals eliminates energy conversion into electric signals, as well as the noise associated with electronic signal processing. In addition to the speed and noise characteristics, the optical processors are also more compact and immune to electrical inference problems.

近期论文

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Optical Bleaching in Continuous Laser Excited Photothermal Lens Spectrometry Agnès Chartier and Stephen E. Bialkowski Applied Spectroscopy 55, 84-91 2001 Comparison of Detection Limits and Relative Responses for Alternative Fluorocarbons by GC-ECD, GC-AED, and GC-MS Sonia R. Sousa and Stephen E. Bialkowski Analytica Chimica Acta 433 (2), 181-186 2001 Modeling Maxwell-Wagner and diffuse double layer polarization in low frequency impedance spectra of clay suspensions Stephen E. Bialkowski, Lynn M. Dudley, and Dani Or in: K. Kupfer (ed.) Fourth Workshop on Electromagnetic Wave Interactions with Moist Substances MFPA, Wiemar, Germany. 2001 Using expectation maximization to obtain dielectric relaxation time spectra of aqueous montmorillonite clay suspensions Stephen E. Bialkowski, Lynn M. Dudley, and Dani Or in: K. Kupfer (ed.) Fourth Workshop on Electromagnetic Wave Interactions with Moist Substances MFPA, Wiemar, Germany. 2001 Photothermal Spectrometry in Small Liquid Channels Agnes B. Chartier and Stephen E. Bialkowski Analytical Science (Japan) 17, i99-i101 2002 Using an Expectation-Maximization Algorithm to Obtain Dielectric Relaxation Time Spectra of Aqueous Montmorillonite Clay Suspensions Stephen E. Bialkowski, Lynn Dudley, and Dani Or Applied Spectroscopy 56 1470-1474 2002 Low Frequency Impedance Behavior of Montmorillonite Suspensions: Polarization Mechanisms in the Low Frequency Domain Lynn M. Dudley, Stephen E. Bialkowski, Dani Or, and Chad Junkermeier, Soil Science Society of America Journal 67 518-526 2003 Steady-State Absorption Rate Models for Use in Relaxation Rate Studies with Continuous Laser Excited Photothermal Lens Spectrometry Stephen E. Bialkowski Photochemical & Photobiological Sciences 2 779-787 2003 Infrared Spectroscopy: Photothermal Stephen E Bialkowski, In Encyclopedia of Analytical Science, 2nd Edition, pages 426-430, Elsevier, Oxford UK 2004 Quantities, Terminology, and Symbols in Photothermal and Related Spectroscopies Masahide Terazima, Noboru Hirota, Silvia E. Braslavsky, Andreas Mandelis, Stephen E. Bialkowski, Gerald J. Diebold, R. J. D. Miller, Danièle Fournier, Richard A. Palmer, and Andy Tam Pure and Applied Chemistry 76 1083-1118 2004 Continuous Laser-Excited Photothermal Spectrometry of CdSxSe1-x Doped Glasses Oluwatosin Dada, Matthew R. Jorgensen, Stephen E. Bialkowski Applied Spectroscopy 61 1373-1378 2007 Finite Element Analysis Modeling of Pulse-Laser Excited Photothermal Deflection (Mirage Effect) from Aerosols Oluwatosin O. Dada and Stephen E. Bialkowski Applied Spectroscopy 62 102 2008 Development of Infrared Photothermal Deflection Spectroscopy (Mirage Effect) for Analysis of Condensed-phase Aerosols Collected in a Micro-Orifice Uniform Deposit Impactor Oluwatosin O. Dada and Stephen E. Bialkowski Applied Spectroscopy 62 112 2008 Pulsed-Laser Excited Photothermal Study of Cadmium Sulfoselenium Nanoparticle Doped Glasses Prakash R. Joshi, Oluwatosin O. Dada and Stephen E. Bialkowski Applied Spectroscopy 63 815 2009 Pulsed Laser Excited Photothermal Lens Spectrometry of Cadmium Sulfoselenide Doped Silica Glasses Prakash R. Joshi, Oluwatosin O. Dada and Stephen E. Bialkowski Journal of Physics: Conference Series 214 012117 2010 Analytical Solution for Mode-Mismatched Thermal Lens Spectroscopy with Sample-Fluid Heat Coupling Luis C. Malacarne, Nelson G. C. Astrath, Paulo R. B. Pedreira, Renio S. Mendes, Mauro L. Baesso, Prakash R. Joshi and Stephen E. Bialkowski Journal of Applied Physics 107 053104 2010 Pulsed-Laser Excited Thermal Lens Spectroscopy With Sample-Fluid Heat Coupling Nelson G. C. Astrath, Luis C. Malacarne, Paulo R. B. Pedreira, Marcos P. Belancon, Mauro L. Baesso, Prakash R. Joshi and Stephen E. Bialkowski Journal of Applied Physics 107 083512 2010 Time-Resolved Thermal Lens and Thermal Mirror Spectroscopies with Sample-Fluid Heat Coupling: A Complete Model for Material Characterization Luis C. Malacarne, Nelson G. C. Astrath, Gustavo V. B. Lukasievicz, Ervin K. Lenzi, Mauro L. Baesso and Stephen E. Bialkowski Applied Spectroscopy 65 99 2011 A Compact Pulsed Infrared Laser Excited Photothermal Deflection Spectrometer Oluwatosin O. Dada and Stephen E. Bialkowski Applied Spectroscopy 65 201 2011 A 3-dimensional time-resolved photothermal deflection “Mirage” method N. G. C. Astrath, L. C. Malacarne, G. V. B. Lukasievicz, H. S. Bernabe, J. H. Rohling, M. L. Baesso, J. Shen and S. E. Bialkowski Applied Physics Letters 100 091908 2012