1 Doppler-Limited Absorption and Fluorescence Spectroscopy
with Lasers .................................................. 1
1.1 Advantages of Lasers in Spectroscopy .................... 1
1.2 High-Sensitivity Methods of Absorption Spectroscopy ..... 5
1.2.1 Frequency Modulation ............................. 7
1.2.2 Intracavity Laser Absorption Spectroscopy
ICLAS ........................................... 13
1.2.3 Cavity Ring-Down Spectroscopy (CRDS) ............ 22
1.3 Direct Determination of Absorbed Photons ............... 26
1.3.1 Fluorescence Excitation Spectroscopy ............ 27
1.3.2 Photoacoustic Spectroscopy ...................... 32
1.3.3 Optothermal Spectroscopy ........................ 37
1.4 Ionization Spectroscopy ................................ 42
1.4.1 Basic Techniques ................................ 42
1.4.2 Sensitivity of Ionization Spectroscopy .......... 44
1.4.3 Pulsed Versus CW Lasers for Photoionization ..... 45
1.4.4 Resonant Two-Photon Ionization (RTPI) Combined
with Mass Spectrometry .......................... 47
1.4.5 Thermionic Diode ................................ 49
1.5 Optogalvanic Spectroscopy .............................. 50
1.6 Velocity-Modulation Spectroscopy ....................... 53
1.7 Laser Magnetic Resonance and Stark Spectroscopy ........ 54
1.7.1 Laser Magnetic Resonance ........................ 55
1.7.2 Stark Spectroscopy .............................. 57
1.8 Laser-Induced Fluorescence ............................. 58
1.8.1 Molecular Spectroscopy by Laser-Induced
Fluorescence .................................... 59
1.8.2 Experimental Aspects of LIF ..................... 61
1.8.3 LIF of Polyatomic Molecules ..................... 65
1.8.4 Determination of Population Distributions
by LIF .......................................... 66
1.9 Comparison Between the Different Methods ............... 69
Problems ............................................... 73
2 Nonlinear Spectroscopy ...................................... 77
2.1 Linear and Nonlinear Absorption ........................ 77
2.2 Saturation of Inhomogeneous Line Profiles .............. 86
2.2.1 Hole Burning .................................... 86
2.2.2 LambDip ......................................... 90
2.3 Saturation Spectroscopy ................................ 93
2.3.1 Experimental Schemes ............................ 93
2.3.2 Cross-Over Signals .............................. 98
2.3.3 Intracavity Saturation Spectroscopy ............. 99
2.3.4 Lamb-Dip Frequency Stabilization of Lasers ..... 102
2.4 Polarization Spectroscopy ............................. 103
2.4.1 Basic Principle ................................ 104
2.4.2 Line Profiles of Polarization Signals .......... 106
2.4.3 Magnitude of Polarization Signals .............. 1ll
2.4.4 Sensitivity of Polarization Spectroscopy ....... 114
2.4.5 Advantages of Polarization Spectroscopy ........ 117
2.5 Multiphoton Spectroscopy .............................. 118
2.5.1 Two-Photon Absorption .......................... 118
2.5.2 Doppler-Free Multiphoton Spectroscopy .......... 121
2.5.3 Influence of Focusing on the Magnitude of
Two-Photon Signals ............................. 125
2.5.4 Examples of Doppler-Free Two-Photon
Spectroscopy ................................... 126
2.5.5 Multiphoton Spectroscopy ....................... 129
2.6 Special Techniques of Nonlinear Spectroscopy .......... 131
2.6.1 Saturated Interference Spectroscopy ............ 131
2.6.2 Doppler-Free Laser-Induced Dichroism
and Birefringence .............................. 134
2.6.3 Heterodyne Polarization Spectroscopy ........... 136
2.6.4 Combination of Different Nonlinear
Techniques ..................................... 137
2.7 Conclusion ............................................ 139
Problems .............................................. 139
3 Laser Raman Spectroscopy ................................... 141
3.1 Basic Considerations .................................. 141
3.2 Experimental Techniques of Linear Laser Raman
Spectroscopy .......................................... 146
3.3 Nonlinear Raman Spectroscopy .......................... 153
3.3.1 Stimulated Raman Scattering .................... 153
3.3.2 Coherent Anti-Stokes Raman Spectroscopy ........ 159
3.3.3 Resonant CARS and BOX CARS ..................... 163
3.3.4 Hyper-Raman Effect ............................. 165
3.3.5 Summary of Nonlinear Raman Spectroscopy ........ 166
3.4 Special Techniques .................................... 167
3.4.1 Resonance Raman Effect ......................... 167
3.4.2 Surface-Enhanced Raman Scattering .............. 168
3.4.3 Raman Microscopy ............................... 168
3.4.4 Time-Resolved Raman Spectroscopy ............... 169
3.5 Applications of Laser Raman Spectroscopy .............. 170
Problems .............................................. 172
4 Laser Spectroscopy in Molecular Beams ...................... 175
4.1 Reduction of Doppler Width ............................ 175
4.2 Adiabatic Cooling in Supersonic Beams ................. 184
4.3 Formation and Spectroscopy of Clusters and Van der
Waals Molecules in Cold Molecular Beams ............... 192
4.4 Nonlinear Spectroscopy in Molecular Beams ............. 197
4.5 Laser Spectroscopy in Fast Ion Beams .................. 200
4.6 Applications of FIBLAS ................................ 203
4.6.1 Spectroscopy of Radioactive Elements ........... 203
4.6.2 Photofragmentation Spectroscopy of Molecular
Ions ........................................... 203
4.6.3 Laser Photodetachment Spectroscopy ............. 205
4.6.4 Saturation Spectroscopy in Fast Beams .......... 206
4.7 Spectroscopy in Cold Ion Beams ........................ 207
4.8 Combination of Molecular Beam Laser Spectroscopy
and Mass Spectrometry ................................. 209
Problems .............................................. 211
5 Optical Pumping and Double-Resonance Techniques ............ 213
5.1 Optical Pumping ....................................... 214
5.2 Optical-RF Double-Resonance Technique ................. 220
5.2.1 Basic Considerations ........................... 220
5.2.2 Laser-RF Double-Resonance Spectroscopy in
Molecular Beams ................................ 223
5.3 Optical-Microwave Double Resonance .................... 226
5.4 Optical-Optical Double Resonance ...................... 230
5.4.1 Simplification of Complex Absorption Spectra ... 231
5.4.2 Stepwise Excitation and Spectroscopy of
Rydberg States ................................. 235
5.4.3 Stimulated Emission Pumping .................... 244
5.5 Special Detection Schemes of Double-Resonance
Spectroscopy .......................................... 247
5.5.1 OODR-Polarization Spectroscopy ................. 247
5.5.2 Polarization Labeling .......................... 250
5.5.3 Microwave-Optical Double-Resonance
Polarization Spectroscopy ...................... 251
5.5.4 Hole-Burning and Ion-Dip Double-Resonance
Spectroscopy ................................... 252
5.5.5 Triple-Resonance Spectroscopy .................. 254
5.5.6 Photoassociation Spectroscopy .................. 255
Problems .............................................. 256
6 Time-Resolved Laser Spectroscopy ........................... 259
6.1 Generation of Short Laser Pulses ...................... 260
6.1.1 Time Profiles of Pulsed Lasers ................. 260
6.1.2 Q-Switched Lasers .............................. 262
6.1.3 Cavity Dumping ................................. 264
6.1.4 Mode Locking of Lasers ......................... 266
6.1.5 Generation of Femtosecond Pulses ............... 275
6.1.6 Optical Pulse Compression ...................... 282
6.1.7 Sub 10-fs Pulses with Chirped Laser Mirrors .... 286
6.1.8 Fiber Lasers and Optical Solitons .............. 290
6.1.9 Wavelength-Tunable Ultrashort Pulses ........... 293
6.1.10 Shaping of Ultrashort Light Pulses ............. 298
6.1.11 Generation of High-Power Ultrashort Pulses ..... 298
6.1.12 Reaching the Attosecond Range .................. 306
6.1.13 Summary of Short Pulse Generation .............. 310
6.2 Measurement of Ultrashort Pulses ...................... 310
6.2.1 Streak Camera .................................. 311
6.2.2 Optical Correlator for Measuring Ultrashort
Pulses ......................................... 312
6.2.3 FROG Technique ................................. 323
6.2.4 SPIDER Technique ............................... 325
6.3 Lifetime Measurement with Lasers ...................... 326
6.3.1 Phase-Shift Method ............................. 330
6.3.2 Single-Pulse Excitation ........................ 332
6.3.3 Delayed-Coincidence Technique .................. 333
6.3.4 Lifetime Measurements in Fast Beams ............ 335
6.4 Spectroscopy in the Pico-to-Attosecond Range .......... 338
6.4.1 Pump-and-Probe Spectroscopy of Collisional
Relaxation in Liquids .......................... 340
6.4.2 Electronic Relaxation in Semiconductors ........ 341
6.4.3 Femtosecond Transition State Dynamics .......... 342
6.4.4 Real-Time Observations of Molecular
Vibrations ..................................... 344
6.4.5 Attosecond Spectroscopy of Atomic Inner Shell
Processes ...................................... 346
6.4.6 Transient Grating Techniques ................... 348
Problems .............................................. 349
7 Coherent Spectroscopy ...................................... 351
7.1 Level-Crossing Spectroscopy ........................... 352
7.1.1 Classical Model of the Hanle Effect ............ 353
7.1.2 Quantum-Mechanical Models ...................... 357
7.1.3 Experimental Arrangements ...................... 359
7.1.4 Examples ....................................... 360
7.1.5 Stimulated Level-Crossing Spectroscopy ......... 362
7.2 Quantum-Beat Spectroscopy ............................. 365
7.2.1 Basic Principles ............................... 365
7.2.2 Experimental Techniques ........................ 367
7.2.3 Molecular Quantum-Beat Spectroscopy ............ 371
7.3 STIRAP Technique ...................................... 372
7.4 Excitation and Detection of Wave Packets in Atoms
and Molecules ......................................... 374
7.5 Optical Pulse-Train Interference Spectroscopy ......... 376
7.6 Photon Echoes ......................................... 379
7.7 Optical Nutation and Free-Induction Decay ............. 385
7.8 Heterodyne Spectroscopy ............................... 387
7.9 Correlation Spectroscopy .............................. 389
7.9.1 Basic Considerations ........................... 389
7.9.2 Homodyne Spectroscopy .......................... 394
7.9.3 Heterodyne Correlation Spectroscopy ............ 397
7.9.4 Fluorescence Correlation Spectroscopy and
Single Molecule Detection ...................... 398
Problems .............................................. 400
8 Laser Spectroscopy of Collision Processes .................. 403
8.1 High-Resolution Laser Spectroscopy of Collisional
Line Broadening and Line Shifts ....................... 404
8.1.1 Sub-Doppler Spectroscopy of Collision
Processes ...................................... 405
8.1.2 Combination of Different Techniques ............ 407
8.2 Measurements of Inelastic Collision Cross Sections
of Excited Atoms and Molecules ........................ 409
8.2.1 Measurements of Absolute Quenching Cross
Sections ....................................... 410
8.2.2 Collision-Induced Rovibronic Transitions
in Excited States .............................. 411
8.2.3 Collisional Transfer of Electronic Energy ...... 416
8.2.4 Energy Pooling in Collisions Between Excited
Atoms .......................................... 417
8.2.5 Spectroscopy of Spin-Flip Transitions .......... 419
8.3 Spectroscopic Techniques for Measuring Collision-
Induced Transitions in the Electronic Ground State
of Molecules .......................................... 421
8.3.1 Time-Resolved Infrared Fluorescence
Detection ...................................... 422
8.3.2 Time-Resolved Absorption and Double-Resonance
Methods ........................................ 423
8.3.3 Collision Spectroscopy with Continuous-Wave
Lasers ......................................... 426
8.3.4 Collisions Involving Molecules in High
Vibrational States ............................. 427
8.4 Spectroscopy of Reactive Collisions ................... 429
8.5 Spectroscopic Determination of Differential
Collision Cross Sections in Crossed Molecular Beams ... 434
8.6 Photon-Assisted Collisional Energy Transfer ...... 439
Problems .............................................. 444
9 New Developments in Laser Spectroscopy ..................... 447
9.1 Optical Cooling and Trapping of Atoms ................. 447
9.1.1 Photon Recoil .................................. 448
9.1.2 Measurement of Recoil Shift .................... 450
9.1.3 Optical Cooling by Photon Recoil ............... 452
9.1.4 Experimental Arrangements ...................... 455
9.1.5 Threedimensional Cooling of Atoms; Optical
Mollasses ...................................... 461
9.1.6 Cooling of Molecules ........................... 464
9.1.7 Optical Trapping of Atoms ...................... 466
9.1.8 Optical Cooling Limits ......................... 473
9.1.9 Bose-Einstein Condensation ..................... 476
9.1.10 Evaporative Cooling ............................ 477
9.1.11 ВЕС of Molecules ............................... 480
9.1.12 Applications of Cooled Atoms and Molecules ..... 481
9.2 Spectroscopy of Single Ions ........................... 483
9.2.1 Trapping of Ions ............................... 483
9.2.2 Optical Sideband Cooling ....................... 487
9.2.3 Direct Observations of Quantum Jumps ........... 490
9.2.4 Formation of Wigner Crystals in Ion Traps ...... 491
9.2.5 Laser Spectroscopy of Ions in Storage Rings .... 493
9.3 Optical Ramsey Fringes ................................ 495
9.3.1 Basic Considerations ........................... 495
9.3.2 Two-Photon Ramsey Resonance .................... 499
9.3.3 Nonlinear Ramsey Fringes Using Three
Separated Fields ............................... 502
9.3.4 Observation of Recoil Doublets and
Suppression of One Recoil Component ............ 505
9.4 Atom Interferometry ................................... 505
9.4.1 Mach-Zehnder Atom Interferometer ............... 507
9.4.2 AtomLaser ...................................... 509
9.5 The One-Atom Maser .................................... 510
9.6 Spectral Resolution Within the Natural Linewidth ...... 514
9.6.1 Time-Gated Coherent Spectroscopy ............... 514
9.6.2 Coherence and Transit Narrowing ................ 518
9.6.3 Raman Spectroscopy with Subnatural
Linewidth ...................................... 520
9.7 Absolute Optical Frequency Measurement and Optical
Frequency Standards ................................... 522
9.7.1 Microwave-Optical Frequency Chains ............. 523
9.7.2 Optical Frequency Combs ........................ 526
9.8 Squeezing ............................................. 529
9.8.1 Amplitude and Phase Fluctuations of a Light
Wave ........................................... 530
9.8.2 Experimental Realization of Squeezing .......... 534
9.8.3 Application of Squeezing to Gravitational
Wave Detectors ................................. 537
Problems .............................................. 539
10 Applications of Laser Spectroscopy ......................... 541
10.1 Applications in Chemistry ........................ 541
10.1.1 Laser Spectroscopy in Analytical Chemistry ..... 541
10.1.2 Single-Molecule Detection ...................... 545
10.1.3 Laser-Induced Chemical Reactions ............... 546
10.1.4 Coherent Control of Chemical Reactions ......... 550
10.1.5 Laser Femtosecond Chemistry .................... 553
10.1.6 Isotope Separation with Lasers ................. 555
10.1.7 Summary of Laser Chemistry ..................... 558
10.2 Environmental Research with Lasers .................... 558
10.2.1 Absorption Measurements ........................ 559
10.2.2 Atmospheric Measurements with LIDAR ............ 561
10.2.3 Spectroscopic Detection of Water Pollution ..... 568
10.3 Applications to Technical Problems .................... 569
10.3.1 Spectroscopy of Combustion Processes ........... 569
10.3.2 Applications of Laser Spectroscopy
to Materials Science ........................... 571
10.3.3 Laser-Induced Breakdown Spectroscopy (LIBS) .... 573
10.3.4 Measurements of Flow Velocities in Gases and
Liquids ........................................ 573
10.4 Applications in Biology ............................... 575
10.4.1 Energy Transfer in DNA Complexes ............... 575
10.4.2 Time-Resolved Measurements of Biological
Processes ...................................... 576
10.4.3 Correlation Spectroscopy of Microbe
Movements ...................................... 578
10.4.4 Laser Microscope ............................... 580
10.5 Medical Applications of Laser Spectroscopy ............ 583
10.5.1 Applications of Raman Spectroscopy in
Medicine ....................................... 584
10.5.2 Heterodyne Measurements of Ear Drums ........... 586
10.5.3 Cancer Diagnostics and Therapy with the HPD
Technique ...................................... 588
10.5.4 Laser Lithotripsy .............................. 589
10.5.5 Laser-Induced Thermotherapy of Brain Cancer .... 590
10.5.6 Fetal Oxygen Monitoring ........................ 591
10.6 Concluding Remarks .................................... 592
Solutions ..................................................... 593
References .................................................... 623
Subject Index ................................................. 693
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