Professor Dr. Wolfgang Demtröder

Transcription

1 Wolfgang Demtröder Laser Spectroscopy Basic Concepts and Instrumentation Third Edition With 710 Figures,16 Tables 93 Problems and Hints for Solution 13

2 Professor Dr. Wolfgang Demtröder Universität Kaiserslautern Fachbereich Physik Erwin-Schrödinger-Strasse Kaiserslautern,Germany Library of Congress Cataloging-in-Publication Data: Demtröder,W. Laser spectroscopy: basic concepts and instrumentation/ Wolfgang Demtröder. 3rd ed. p. cm. ISBN (alk. paper) 1. Laser spectroscopy. I. Title. QC 454.L3 D dc ISSN ISBN rd Edition Springer-Verlag Berlin Heidelberg New York ISBN X 2nd Edition Springer-Verlag Berlin Heidelberg New York This work is subject to copyright. All rights are reserved,whether the whole or part of the material is concerned,specifically the rights of translation,reprinting,reuse of illustrations,recitation,broadcasting,reproduction on microfilm or in any other way,and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9,1965,in its current version,and permission for use must always be obtained from Springer-Verlag. Violations are liable for prosecution under the German Copyright Law. Springer-Verlag Berlin Heidelberg New York a member of BertelsmannSpringer Science+Business Media GmbH Springer-Verlag Berlin Heidelberg 1981,1996,2003 Printed in Germany The use of general descriptive names,registered names,trademarks,etc. in this publication does not imply,even in the absence of a specific statement,that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Typesetting: Data conversion by Fa. Le-TeX,Leipzig Cover design: design & production GmbH,Heidelberg Printed on acid-free paper SPIN /3141/ba

3 Contents 1. Introduction Absorption and Emission of Light Cavity Modes Thermal Radiation and Planck s Law Absorption, Induced, and Spontaneous Emission Basic Photometric Quantities Definitions Illumination of Extended Areas Polarization of Light Absorption and Emission Spectra Transition Probabilities Lifetimes, Spontaneous and Radiationless Transitions Semiclassical Description: Basic Equations Weak-Field Approximation Transition Probabilities with Broad-Band Excitation Phenomenological Inclusion of Decay Phenomena Interaction with Strong Fields Relations Between Transition Probabilities, Absorption Coefficient, and Line Strength Coherence Properties of Radiation Fields Temporal Coherence Spatial Coherence Coherence Volume The Coherence Function and the Degree of Coherence Coherence of Atomic Systems Density Matrix Coherent Excitation Relaxation of Coherently Excited Systems Problems Widths and Profiles of Spectral Lines Natural Linewidth Lorentzian Line Profile of the Emitted Radiation Relation Between Linewidth and Lifetime Natural Linewidth of Absorbing Transitions Doppler Width... 68

4 XII Contents 3.3 Collisional Broadening of Spectral Lines Phenomenological Description Relations Between Interaction Potential, Line Broadening, and Shifts Collisional Narrowing of Lines Transit-Time Broadening Homogeneous and Inhomogeneous Line Broadening Saturation and Power Broadening Saturation of Level Population by Optical Pumping Saturation Broadening of Homogeneous Line Profiles Power Broadening Spectral Line Profiles in Liquids and Solids Problems Spectroscopic Instrumentation Spectrographs and Monochromators Basic Properties Prism Spectrometer Grating Spectrometer Interferometers Basic Concepts Michelson Interferometer Mach Zehnder Interferometer Multiple-Beam Interference Plane Fabry Perot Interferometer Confocal Fabry Perot Interferometer Multilayer Dielectric Coatings Interference Filters Birefringent Interferometer Tunable Interferometers Comparison Between Spectrometers and Interferometers Spectral Resolving Power Light-Gathering Power Accurate Wavelength Measurements Precision and Accuracy of Wavelength Measurements Today s Wavemeters Detection of Light Thermal Detectors Photodiodes Photodiode Arrays Photoemissive Detectors Detection Techniques and Electronic Equipment Conclusions Problems

5 Contents 5. Lasers as Spectroscopic Light Sources Fundamentals of Lasers Basic Elements of a Laser Threshold Condition Rate Equations Laser Resonators Open Optical Resonators Spatial Field Distributions in Open Resonators Confocal Resonators General Spherical Resonators Diffraction Losses of Open Resonators Stable and Unstable Resonators Ring Resonators Frequency Spectrum of Passive Resonators Spectral Characteristics of Laser Emission Active Resonators and Laser Modes Gain Saturation Spatial Hole Burning Multimode Lasers and Gain Competition Mode Pulling Experimental Realization of Single-Mode Lasers Line Selection Suppression of Transverse Modes Selection of Single Longitudinal Modes Intensity Stabilization Wavelength Stabilization Controlled Wavelength Tuning of Single-Mode Lasers Continuous Tuning Techniques Wavelength Calibration Linewidths of Single-Mode Lasers Tunable Lasers Basic Concepts Semiconductor-Diode Lasers Tunable Solid-State Lasers Color-Center Lasers Dye Lasers Excimer Lasers Free-Electron Lasers Nonlinear Optical Mixing Techniques Physical Background Phase Matching Second-Harmonic Generation Quasi Phase Matching Sum-Frequency and Higher-Harmonic Generation X-Ray Lasers Difference-Frequency Spectrometer XIII

6 XIV Contents Optical Parametric Oscillator Tunable Raman Lasers Gaussian Beams Problems Doppler-Limited Absorption and Fluorescence Spectroscopy with Lasers Advantages of Lasers in Spectroscopy High-Sensitivity Methods of Absorption Spectroscopy Frequency Modulation Intracavity Absorption Cavity Ring-Down Spectroscopy (CRDS) Direct Determination of Absorbed Photons Fluorescence Excitation Spectroscopy Photoacoustic Spectroscopy Optothermal Spectroscopy Ionization Spectroscopy Basic Techniques Sensitivity of Ionization Spectroscopy Pulsed Versus CW Lasers for Photoionization Resonant Two-Photon Ionization Combined with Mass Spectrometry Thermionic Diode Optogalvanic Spectroscopy Velocity-Modulation Spectroscopy Laser Magnetic Resonance and Stark Spectroscopy Laser Magnetic Resonance Stark Spectroscopy Laser-Induced Fluorescence Molecular Spectroscopy by Laser-Induced Fluorescence Experimental Aspects of LIF LIF of Polyatomic Molecules Determination of Population Distributions by LIF Comparison Between the Different Methods Problems Nonlinear Spectroscopy Linear and Nonlinear Absorption Saturation of Inhomogeneous Line Profiles Hole Burning Lamb Dip Saturation Spectroscopy Experimental Schemes Cross-Over Signals Intracavity Saturation Spectroscopy Lamb-Dip Frequency Stabilization of Lasers

7 Contents 7.4 Polarization Spectroscopy Basic Principle Line Profiles of Polarization Signals Magnitude of Polarization Signals Sensitivity of Polarization Spectroscopy Advantages of Polarization Spectroscopy Multiphoton Spectroscopy Two-Photon Absorption Doppler-Free Multiphoton Spectroscopy Influence of Focusing on the Magnitude of Two-Photon Signals Examples of Doppler-Free Two-Photon Spectroscopy Multiphoton Spectroscopy Special Techniques of Nonlinear Spectroscopy Saturated Interference Spectroscopy Doppler-Free Laser-Induced Dichroism and Birefringence Heterodyne Polarization Spectroscopy Combination of Different Nonlinear Techniques Conclusion Problems Laser Raman Spectroscopy Basic Considerations Experimental Techniques of Linear Laser Raman Spectroscopy Nonlinear Raman Spectroscopy Stimulated Raman Scattering Coherent Anti-Stokes Raman Spectroscopy Resonant CARS and BOX CARS Hyper-Raman Effect Summary of Nonlinear Raman Spectroscopy Special Techniques Resonance Raman Effect Surface-Enhanced Raman Scattering Raman Microscopy Time-Resolved Raman Spectroscopy Applications of Laser Raman Spectroscopy Problems Laser Spectroscopy in Molecular Beams Reduction of Doppler Width Adiabatic Cooling in Supersonic Beams Formation and Spectroscopy of Clusters and Van der Waals Molecules in Cold Molecular Beams Nonlinear Spectroscopy in Molecular Beams XV

8 XVI Contents 9.5 Laser Spectroscopy in Fast Ion Beams Applications of FIBLAS Spectroscopy of Radioactive Elements Photofragmentation Spectroscopy of Molecular Ions Laser Photodetachment Spectroscopy Saturation Spectroscopy in Fast Beams Spectroscopy in Cold Ion Beams Combination of Molecular Beam Laser Spectroscopy and Mass Spectrometry Problems Optical Pumping and Double-Resonance Techniques Optical Pumping Optical RF Double-Resonance Technique Basic Considerations Laser RF Double-Resonance Spectroscopy in Molecular Beams Optical Microwave Double Resonance Optical Optical Double Resonance Simplification of Complex Absorption Spectra Stepwise Excitation and Spectroscopy of Rydberg States Stimulated Emission Pumping Special Detection Schemes of Double-Resonance Spectroscopy OODR-Polarization Spectroscopy Polarization Labeling Microwave-Optical Double-Resonance Polarization Spectroscopy Hole-Burning and Ion-Dip Double-Resonance Spectroscopy Triple-Resonance Spectroscopy Problems Time-Resolved Laser Spectroscopy Generation of Short Laser Pulses Time Profiles of Pulsed Lasers Q-Switched Lasers Cavity Dumping Mode Locking of Lasers Generation of Femtosecond Pulses Optical Pulse Compression Sub 10-fs Pulses with Chirped Laser Mirrors Fiber Lasers and Optical Solitons Shaping of Ultrashort Light Pulses Generation of High-Power Ultrashort Pulses

9 Contents XVII 11.2 Measurement of Ultrashort Pulses Streak Camera Optical Correlator for Measuring Ultrashort Pulses Lifetime Measurement with Lasers Phase-Shift Method Single-Pulse Excitation Delayed-Coincidence Technique Lifetime Measurements in Fast Beams Pump-and-Probe Technique Pump-and-Probe Spectroscopy of Collisional Relaxation in Liquids Electronic Relaxation in Semiconductors Femtosecond Transition State Dynamics Real-Time Observations of Molecular Vibrations Transient Grating Techniques Problems Coherent Spectroscopy Level-Crossing Spectroscopy Classical Model of the Hanle Effect Quantum-Mechanical Models Experimental Arrangements Examples Stimulated Level-Crossing Spectroscopy Quantum-Beat Spectroscopy Basic Principles Experimental Techniques Molecular Quantum-Beat Spectroscopy Excitation and Detection of Wave Packets in Atoms and Molecules Optical Pulse-Train Interference Spectroscopy Photon Echoes Optical Nutation and Free-Induction Decay Heterodyne Spectroscopy Correlation Spectroscopy Basic Considerations Correlation Spectroscopy of Light Scattered by Microparticles Homodyne Spectroscopy Heterodyne Correlation Spectroscopy Fluorescence Correlation Spectroscopy and Single Molecule Detection Problems

10 XVIII Contents 13. Laser Spectroscopy of Collision Processes High-Resolution Laser Spectroscopy of Collisional Line Broadening and Line Shifts Sub-Doppler Spectroscopy of Collision Processes Combination of Different Techniques Measurements of Inelastic Collision Cross Sections of Excited Atoms and Molecules Measurements of Absolute Quenching Cross Sections Collision-Induced Rovibronic Transitions in Excited States Collisional Transfer of Electronic Energy Energy Pooling in Collisions Between Excited Atoms Spectroscopy of Spin-Flip Transitions Spectroscopic Techniques for Measuring Collision-Induced Transitions in the Electronic Ground State of Molecules Time-Resolved Infrared Fluorescence Detection Time-Resolved Absorption and Double-Resonance Methods Collision Spectroscopy with Continuous-Wave Lasers Collisions Involving Molecules in High Vibrational States Spectroscopy of Reactive Collisions Spectroscopic Determination of Differential Collision Cross Sections in Crossed Molecular Beams Photon-Assisted Collisional Energy Transfer Photoassociation Spectroscopy of Colliding Atoms Problems New Developments in Laser Spectroscopy Optical Cooling and Trapping of Atoms Photon Recoil Measurement of Recoil Shift Optical Cooling by Photon Recoil Experimental Arrangements Threedimensional Cooling of Atoms; Optical Mollasses Cooling of Molecules Optical Trapping of Atoms Optical Cooling Limits Bose Einstein Condensation Evaporative Cooling Applications of Cooled Atoms and Molecules

11 Contents XIX 14.2 Spectroscopy of Single Ions Trapping of Ions Optical Sideband Cooling Direct Observations of Quantum Jumps Formation of Wigner Crystals in Ion Traps Laser Spectroscopy in Storage Rings Optical Ramsey Fringes Basic Considerations Two-Photon Ramsey Resonance Nonlinear Ramsey Fringes Using Three Separated Fields Observation of Recoil Doublets and Suppression of One Recoil Component Atom Interferometry Mach Zehnder Atom Interferometer Atom Laser The One-Atom Maser Spectral Resolution Within the Natural Linewidth Time-Gated Coherent Spectroscopy Coherence and Transit Narrowing Raman Spectroscopy with Subnatural Linewidth Absolute Optical Frequency Measurement and Optical Frequency Standards Microwave Optical Frequency Chains Frequency Comb from Femtosecond Laser Pulses Squeezing Amplitude and Phase Fluctuations of a Light Wave Experimental Realization of Squeezing Application of Squeezing to Gravitational Wave Detectors Applications of Laser Spectroscopy Applications in Chemistry Laser Spectroscopy in Analytical Chemistry Single-Molecule Detection Laser-Induced Chemical Reactions Coherent Control of Chemical Reactions Laser Femtosecond Chemistry Isotope Separation with Lasers Summary of Laser Chemistry Environmental Research with Lasers Absorption Measurements Atmospheric Measurements with LIDAR Spectroscopic Detection of Water Pollution Applications to Technical Problems Spectroscopy of Combustion Processes

12 XX Contents Applications of Laser Spectroscopy to Materials Science Measurements of Flow Velocities in Gases and Liquids Applications in Biology Energy Transfer in DNA Complexes Time-Resolved Measurements of Biological Processes Correlation Spectroscopy of Microbe Movements Laser Microscope Time-Resolved Spectroscopy of Biological Processes Medical Applications of Laser Spectroscopy Applications of Raman Spectroscopy in Medicine Heterodyne Measurements of Ear Drums Cancer Diagnostics and Therapy with the HPD Technique Laser Lithotripsy Laser-Induced Thermotherapy of Brain Cancer Fetal Oxygen Monitoring Concluding Remarks References Subject Index

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