Lasers in Chemical Analysis

ISBN-13: 9781461260110 / Angielski / Miękka / 2012 / 310 str.

Gary M. Hieftje; John Travis; Fred E. Lytle

Opis

Lasers are relatively recent additions to the analytical scientist's arsenal. Because of this, many analysts-whether their concern is research or some range of applications-are in need of a tutorial introduction not only to the principles of lasers, their optics, and radiation, but also to their already diverse and burgeoning applications. The artic1es presented in this volume, carefully enhanced and edited from lectures prepared for the ACS Division of Analytical Chemistry 1979 Summer Symposium, are designed to provide just such a broad introduction to the subject. Thus, in addition to several excellent chapters on laser fundamentals, there are many practically oriented artic1es dealing with laser analytical methodology, inc1uding techniques based on the absorption oflaser radiation, on laser-induced fluorescence, and on some of the uses of lasers in chemical instru- mentation. The first of these sections is pivotal and reflects in part our philosophy in organizing this collection. The authors of the initial chapters were invited not only because of their expertise in the field of lasers and analytical chemistry, but also because their didactic approach to writing and their c1arity of presentation were well known to us. It is our hope that individual readers with little knowledge of lasers will gain from these introductory chapters sufficient information to render the later, more detailed artic1es both useful and meaningful.

Spis treści

Section One Lasers and Laser Optics.- 1 Laser Fundamentals.- 1. Introduction.- 2. The Optical Amplifier.- 2.1. Thermal Energy Distribution.- 2.2. Absorption of Radiation.- 2.3. Spontaneous Emission of Radiation.- 2.4. Stimulated Emission of Radiation.- 2.5. Kinetic Picture of a Two-Level System.- 2.6. Inclusion of Losses.- 2.7. Transition Bandwidth.- 2.8. Saturated Gain.- 3. The Excited-State Pump.- 3.1. Optically Pumping a Three-Level System.- 3.2. Optically Pumping a Four-Level System.- 3.3. Pumping by a Gas Discharge.- 3.4. Pumping by a Chemical Reaction.- 3.5. Pumping in a Semiconductor.- 4. The Optical Resonator.- 4.1. Gains and Losses in an Oscillator.- 4.2. Diffraction in the Resonator.- 4.3. Resonator Modes.- 4.4. Polarization.- 2 Tunable Laser Systems.- 1. Introduction.- 2. Dye Lasers.- 2.1. Gain Media.- 2.2. Pump Sources.- 2.3. Resonator Characteristics.- 3. Other Tunable lasers.- 3.1. F-Center Lasers.- 3.2. Diode Lasers.- 3.3. Free Electron Lasers.- 4. Concluding Remarks.- References.- 3 Pulsed Laser Systems.- 1. Introduction.- 2. Methodology of Pulsed Lasers.- 2.1. Pulsed Excitation.- 2.2. Q-Switching.- 2.3. Cavity Dumping.- 2.4. Mode-Locking.- 3. Characterization of the Pulsed Lasers.- References.- 4 Nonlinear Optics.- 1. Introduction.- 2. Nonlinear Polarization Effects.- 2.1. Second-Order Optical Effects.- 2.2. Third-Order Optical Effects.- 3. Nonlinear Raman Processes.- 3.1. CARS, CSRS, and HORSES.- 3.2. Raman Gain and Loss Spectroscopy.- 3.3. Phase Matching in Nonlinear Raman Methods.- 3.4. Stimulated Raman Scattering.- Acknowledgments.- References.- Section Two Methods Based on Absorption of Laser Radiation.- 5 The Optogalvanic Effect.- 1. Introduction.- 2. Historical and Contemporary Perspectives.- 2.1. Pre-Laser Manifestations of the OGE.- 2.2. Selective Ionization with Tunable Lasers.- 3. Applications of the Optogalvanic Effect.- 3.1. Calibration of Tunable Lasers.- 3.2. Spectroscopy and Discharge Diagnostics.- 3.3. Trace Analysis.- 4. Laser-Enhanced Ionization Spectrometry in Flames.- 4.1. Experimental Method.- 4.2. Analytical Results.- 5. Theory.- 5.1. Ion Production.- 5.2. Signal Collection.- 6. Analytical Method Development.- 6.1. Advantage.- 6.2. Problem Areas.- 6.3. Avenues for Improvement.- 6.4. Future Directions.- 7. Conclusions.- References.- 6 Potential Analytical Aspects of Laser Multiphoton Ionization Mass Sectrometry.- 1. Introduction.- 2. The REMPI Process.- 3. Typical Results: Vibronic/Mass Spectra.- 4. Sensitivity of Laser MPI Mass Spectrometry.- 5. Possible Practical Applications and Future Potentials of LAMS.- Acknowledgment.- References.- 7 Analytical Aspects of Thermal Lensing Spectroscopy.- 1. Introduction.- 2. Observation of the Thermal Lens Effect.- 3. Measurement of Small Absorption.- 4. Model of the Thermal Lens Effect.- 5. Application of the Thermal Lens to Absorption Spectroscopy.- 6. Application of the Thermal Lens to Analytical Chemistry.- 7. Other Thermo-Optical Techniques.- 8. Conclusion.- References.- Section Three Methods Based on Laser-Induced Fluorescence.- 8 Laser-Excited Atomic Fluorescence Spectrometry.- 1. Introduction.- 2. Overview of Lasers and AFS.- 2.1. LEAFS Process.- 2.2. Laser and AFS Link.- 2.3. Criteria in Choosing an Excitation Source for AFS.- 3. Fundamental Considerations.- 3.1. Types of Atomic Fluorescence Transitions.- 3.2. Spectral Interferences.- 3.3. Optimization of Optical Transfer.- 3.4. Fluorescence Radiance Expressions.- 4. Experimental Considerations.- 5. Experimental Results.- 6. Conclusion.- References.- 9 Laser-Excited Fluorescence Spectroscopy.- 1. Introduction.- 2. Laser-Excited Atomic Fluorescence.- 3. Laser-Excited Molecular Fluorescence.- 4. Probe-Ion Methods.- 5. Conclusions.- References.- 10 Laser-Excited Matrix-Isolation Molecular Fluorescence Spectrometry.- 1. Matrix Isolation Spectroscopy.- 2. How Can Laser Excitation Increase the Analytical Utility of MI Fluorimetry?.- 3. Time-Resolved Fluorescence Spectroscopy.- 4. “Pseudo-Shpolskii” and Site-Selection Fluorimetry.- 5. MI Fluorescence for High-Resolution Gas Chromatographic Detection.- 6. Conclusion.- Acknowledgment.- References.- 11 Laser-Induced Fluorimetric Analysis of Drugs in Biological Fluids.- 1. Introduction.- 2. Experimental.- 2.1. Instrumentation.- 2.2. Reagents.- 2.3. Compounds Examined.- 3. Results and Discussion.- Acknowledgment.- References.- 12 New Laser-Based Methodologies for the Determination of Organic Pollutants Via Fluorescence.- 1. Introduction.- 2. Theory.- 2.1. Fluorescence Line-Narrowing Spectroscopy.- 2.2. Gas Chromatography—Rotationally Cooled Fluorescence.- 3. Experimental.- 3.1. Fluorescence Line-Narrowing Spectroscopy.- 3.2. Gas Chromatography—Rotationally Cooled Fluorescence.- 4. Results and Discussion.- 4.1. Fluorescence Line-Narrowing Spectroscopy.- 4.2. Gas Chromatography—Rotationally Cooled Fluorescence.- Acknowledgment.- References.- 13 Trace Analysis of Nonfluorescent Ions by Association with a Fluorescent Probe in the Solid State.- 1. Introduction.- 2. Experimental.- 3. Site Equilibria and Application to Chemical Analysis.- 4. Interferences.- Acknowledgment.- References.- Section Four Lasers in Analytical Instrumentation.- 14 Laser-Based Detectors for Liquid Chromatography.- 1. Introduction.- 2. Laser Properties Relevant to HPLC Detector Design.- 2.1. Collimation.- 2.2. Monochromaticity.- 2.3. Power.- 2.4. Temporal Resolution.- 3. Some Laser-Based HPLC Detectors.- 3.1. Fluorescence.- 3.2. Two-Photon Excited Fluorescence.- 3.3. Coherent Anti-Stokes Raman Scattering (CARS).- 3.4. Light Scattering.- 4. Future Developments.- 4.1. Optical Activity.- 4.2. Raman-Induced Kerr-Effect Spectroscopy.- 4.3. Refractive Index (RI).- 4.4. Thermal Lensing.- 5. Summary.- Acknowledgments.- References.- 15 Lasers and Analytical Polarimetry.- 1. Introduction.- 2. Principles of Polarimetry.- 3. Sensitivity Enhancement.- 4. Accuracy Improvement.- 5. Conclusion.- References.