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Femtochemistry Femtochemistry Edited by Frans C. De Schryver, Steven De Feyter, and Gerd Schweitzer With the Nobel Lecture ofA. Zeivail WILEY-VCH Weinheim - New-York - Chichester - Brisbane - Singapore - Toronto Contents Preface XV List of Contributors XVII 1 Femtochemistry: Atomic-Scale Dynamics of the Chemical Bond Using Ultrafast Lasers (Nobel Lecture) 1 Ahmed H. Zewail 1.1 Prologue 1 1.2 Dynamics and Arrow of Time 10 1.2.1 Origins—From Kinetics To Dynamics 10 1.2.1.1 The Arrhenius Seminal Contribution 10 1.2.1.2 The London, Eyring, and Polanyi Contributions 11 1.2.1.3 The Transition State and its Definition 12 1.2.1.4 The Transition State and its Spectroscopy 14 1.2.2 The Arrow of Time 14 1.3 Femtochemistry: Development of the Field 17 1.3.1 The Early Yearsof Coherence 17 1.3.1.1 New Techniques for Molecules 17 1.3.1.2 The Optical Analogue of NMR Spectroscopy: Controlling the Phase 1.3.2 The Marriage with Molecular Beams 22 1.3.2.1 The Anthracene Discovery: A Paradigm Shift 23 1.3.2.2 The Successful 036 Laboratory 25 1.3.2.3 Changing A Dogma: Development ofRCS 27 1.3.3 The Transition to the Sub-Picosecond Regime 29 1.3.3.1 A New Beam Machine: Pump-Probe Mass Spectrometry 29 1.3.3.2 The First Experiment on ICN: Sub-picosecond Resolution 30 1.3.4 The Femtosecond Dream 32 1.3.4.2 The Classic Femtosecond Discovery in ICN 32 1.3.4.3 The NaI Discovery: A Paradigm for the Field 35 1.3.4.4 The Saddle-Point Transition State 38 1.3.4.5 The Uncertainty Principle Paradox 40 1.3.4.6 Bimolecular Bond Making and Bond Breaking: Bemstein's Passion VI Contents 1.3.4.7 Ultrafast Electron Diffraction 43 1.3.4.8 Clusters, Dense Fluids and Liquids, and New Generations of FEMTOLANDS 43 1.3.4.9 Theoretical Femtochemistry 44 1.3.4.10 Experimental Femtochemistry 46 1.3.5 Femtocopia—Examples from Caltech 50 1.3.5.1 Elementary Reactions and Transition States 50 1.3.5.2 Organic Chemistry 50 1.3.5.3 Electron and Proton Transfer 50 1.3.5.4 Inorganic and Atmospheric Chemistry 52 1.3.5.5 The Mesoscopic Phase: Clusters and Nanostructures 54 1.3.5.6 The Condensed Phase: Dense Fluids, Liquids, and Polymers 54 1.3.6 Opportunities for the Future 57 1.3.6.1 Transient Structures from Ultrafast Electron Diffraction 57 1.3.6.2 Reaction Control 58 1.3.6.3 Biological Dynamics 62 1.4 Impact and Concepts—A Retrospective 65 1.4.1 Time Resolution—Reaching the Transition-State Limit 65 1.4.2 Atomic-Scale Resolution 66 1.4.3 Generality of the Approach 66 IAA Some Concepts 67 1.4.4.1 Resonance (Nonequilibrium Dynamics) 67 1.4.4.2 Coherence (Single-Molecule-Type Dynamics) 68 1.4.4.3 Transition Structures (Landscape Dynamics) 69 1.4.4.4 Reduced Space (Directed Dynamics) 69 1.5 Epilogue 70 1.6 Appendix 72 1.6.1 A Primer for Femtoscopy, Coherence and Atoms in Motion 72 1.6.1.1 Pump-Probe Femtoscopy 72 1.6.1.2 Coherence and Atomic Motion 73 2 Transition State Theory and Reaction Dynamics - An Overview 87 Ward H. Thompson, Philip M. Kiefer, and James T. Hynes 2.1 Introduction 87 2.2 Crossing the Transition State in Solution 88 2.3 Acid-Base Proton-Transfer Reactions in Solution 89 2.4 Wave-Packet Evolution for Proton-Transfer Reactions 92 3 Organic Femtochemistry: Oiradicals, Theory and Experiments 97 Steven De Feyter, Eric W.-C. Diau, and Ahmed H. Zewail 3.1 Introduction 97 3.2 Experimental 97 3.3 Tetramethylene, Trimethylene, and the Constrained Diradical[6] 99 3.1 Theoretical: PES and Reaction Pathways 99 3.2 Tetramethylene: Dynamical Time Scales and Stereochemistry 201 3.3 The Constrained Diradical and Trimethylene 104 3.4 PES, IVR, and Entropy Effects 104 4 Diradicals as Intermediates in Norrish Type-II Reactions 106 5 Conclusion 111 The Coulomb Explosion Imaging Method and Excited-State Proton-Transfer Reactions 113 Eric S. Wisniewski, Jason R. Stairs, Daniel E. Folmer, andA. Welford Castlemanjr. 1 Introduction 113 2 Experimental Techniques 116 2.1 Femtosecond Laser System and Amplification 116 2.2 Pump-Probe and Coulomb Explosion Imaging 116 3 Results and Discussion 117 3.1 Coulomb Explosion Imaging Method 117 3.2 Hydration of 7-Azaindole 125 4 Conclusions 129 Femtosecond Dynamics at Conical Intersections 133 Wolfgang Domcke 1 Introduction 133 2 Modeling of Conical Intersections 135 3 Time-Dependent Quantum Wave-Packet and Reduced-Density-Matrix Dynamics 138 4 Aspects of Ultrafast Dynamics at Conical Intersections 139 Femtosecond Spectroscopy of Molecular Caging: Quantum and Classical Approaches 147 Vladimir A Ermoshin, Volker Engel, and Christoph Meier 1 Introduction 147 2 Quantum Treatment 148 3 Classical Treatment 150 4 I2/Ar Caging 150 5 Summary 153 Ultrafast Geometrical Relaxation in Polydiacetylene Induced by Sub-5-fs Pulses 155 Takayoshi Kobayashi 1 Introduction. 155 2 Experimental 156 VIII Contents 7.3 Results and Discussion 257 7.4 Conclusion 166 8 Ultrafast Probing and Control of Molecular Dynamics: Beyond the Pump- Probe Method 169 Marcos Dcmtus 8.1 Introduction 169 8.2 Four-Wave Mixing Techniques 170 8.2.1 Differences Between the Pump-Probe Method and Four-Wave Mix­ ing 170 8.2.2 Off-Resonance FWM 171 8.2.3 On-Resonance FWM 172 8.2.3.1 Controlling Ground or Excited-State Observation 173 8.2.3.2 Inhomogeneous Broadening and Photon-Echo Measurements 274 8.3 Experimental Methods 275 8.4 Results 277 8.4.1 Off-Resonance Measurements 278 8.4.2 Resonance Measurements 279 8.4.3 Coherent Control with FWM 282 8.5 Discussion 283 8.5.1 Off-Resonance FWM and Time-Resolved Measurements of Ground-State Dynamics 283 8.5.2 Resonance FWM, Ground and Excited-State Dynamics 284 9 Quantum Control of Ultrafast Laser-Driven Isomerization Reactions: Proton Transfer and Selective Preparation Of Enantiomers 289 Nadja DoWc, Yuichi Fujimura, Leticia Gonzalez, Kunihito Hoki, Dominik Kröner, Oliver Kühn, Jörn Manz, and Yukiyoshi Ohtsuki 9.1 Introduction 289 9.2 Laser Preparation of Pure Enantiomers 290 9.3 Proton Transfer 293 9.4 Conclusions 297 10 Controlling the Vibration and Dissociation Dynamics in Small Molecules and Clusters 299 Stefan Vajda and Ludger Wöste 10.1 Introduction 299 10.2 The Choice of the Molecular Systems 200 10.3 Experimental Set-Up 204 10.3.1 Molecular Beam and Laser Systems 204 10.3.2 Pulse Shaping 205 10.3.2.1 Simple Pulse Shaping: Generation ofLinearlyChirped Pulses 205 10.3.2.2 Active Feedback Optimization: Search for System-Specific Tailor-Made Pulses 205 10.4 Experimental Results and Discussion 205 10.4.1 Na3 205 10.4.2 Na2K 206 10.4.3 CpMn(CO)3 212 10.5 Summary 214 11 Two-Dimensional Optical Nonlinear Spectroscopy in Liquids 217 Keisuke Tominaga and Hiroaki Maekawa 11.1 Introduction 217 11.2 Calculation of the Two-Dimensional Spectrum 219 11.3 Two-Dimensional Spectrum 221 12 Femtosecond Diffuse Reflectance Spectroscopy and Photochemistry of Organic Microcrystals 225 Hiroshi Masuhara, Tsuyoshi Asahi, and Akihiro Furube 12.1 Introduction 225 12.2 System and Analysis 226 12.2.1 Femtosecond Diffuse Reflectance Spectroscopic System 226 12.2.2 Time-Dependent Kubelka-Munk Model 227 12.2.3 Temporal Characteristics and Time Resolution 229 12.3 Ultrafast Processes in Some Organic Powders 231 12.3.1 Excited Electronic Structure and Dynamics of Weak CT Micro­ crystals 231 12.3.2 Charge Recombination Process of Molecules Adsorbed in Zeolites 233 12.3.3 Intersystem Crossing in an Acridine Microcrystal 234 12.4 Future Perspectives 236 12.4.1 Femtosecond Absorption Spectroscopy ofa Single Microcrystal 236 12.4.2 Femtosecond Light-Scattering Spectroscopy 236 12.4.3 Femtosecond Cooperative Photochromic Reaction in Organic Crystals 237 13 Impurity Rydberg States as Probes of Local Dynamics in the Condensed Phase 239 Franco Vigliotti and Majed Chergui 13.1 Introduction 239 13.2 Steady-State Spectroscopy 240 13.3 Time-Resolved Spectroscopy 244 13.3.1 NO in Solid Ar 244 13.3.2 NO in Solid Ne 245 13.3.3 NO in Solid Hydrogen 246 13.4 Discussion 248 13.4.1 Inertial Response (t < 200 fs) 248 13.4.2 Relaxation Process ( 200 fs < t < 3 ps) 250 13.5 Concluding Remarks 250 X Contents 14 Photoelectron Spectroscopy as a Probe for Investigating Chemical Dynamics 253 Ingo Fischer 14.1 Introduction 253 14.2 The Concept 253 14.3 Molecular Photophysics 256 14.4 Monitoring Wavepacket Dynamics by ZEKE and PE Spectroscopy 259 14.5 Intensity Effects in ZEKE and Photoelectron Spectra 261 14.6 Probing Chemical Dynamics by Photoelectron and ZEKE Spectroscopy in the Frequency Domain 262 14.7 New Directions 263 15 Femtochemistry in Nanocavities 267 Abderrazzak Douhal 15.1 Introduction 267 15.2 Concept of Femtochemistry in Nanocavities 268 15.3 I-I Bond Breaking and Remaking in a Molecular Nanocavity 269 15.4 Intramolecular H-Bond Breaking and Making and Related Reactions in Nanocavities 273 15.5 Concluding Remarks 277 16 Energy- and Angle-Resolved Femtosecond Photoelectron Spectra from Rotating Molecules 281 Yasuki Arasaki, Kazuo Takatsuka, Kwanghsi Wang and Vincent McKoy Abstract 281 16.1 Introduction 281 16.2 Pump-Probe Photoelectron Spectroscopy and Molecular Rotation 282 16.2.1 Formulation 282 16.2.2 Molecular Rotation 286 16.3 Photoelectron Distribution from Rotating Molecules 288 16.3.1 Vibrational Wave Packets 288 16.3.2 Photoelectrons from a Rigid Rotor 288 16.3.3 Convolution of Molecular Vibration and Rotation 289 16.4 Concluding Remarks 292 17 Femtosecond Time-Resolved Fluorescence and Anisotropy Decay Spectroscopy of a Dendrimer with Eight Chromophores at the Rim 295 Gerd Schweitzer, Cino De Beider, Svenjordens, Marc Lor, Klaus Müllen, Andreas Herrmann, and Frans C.
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