Photoionization and Photodetachment

The following sections are included:

• INTRODUCTION

• PREFACE

• CONTENTS

The following sections are included:

• Introduction
  • REMPI, through a Looking Glass
  • Newton Spheres
  • Velocity Mapping in Photodissociation and Photoionization Studies
    • Photodissociation Studies
      • Correlation of internal state and velocity distributions
      • Directional properties
      • Angular distributions — the (μ, ν) correlation, the time-scale of photodissociation, and the spectroscopic signature of excited electronic states
      • The (μ, ν, J) three-vector correlation
      • Coherence effects
    • Photoelectron Studies

• Experimental Section
  • Apparatus
    • Resolution: Factors Affecting Image Quality

• Applications of Velocity Mapping
  • Decomposition of Absorption Continua: Neutral Product Analysis
    • Decomposition of the A-Band of Halogen Containing Species
    • Decomposition of the Herzberg Continuum of Molecular Oxygen
  • Predissociation Angular Distributions — State Lifetimes
  • Super-Excited States

• Conclusions

• References

The following sections are included:

• Introduction

• Theoretical Principles

• Experimental Methods

• Experimental Results
  • Bound-to-Bound Transitions
  • Total Cross-sections of Bound-to-Continuum Transitions
  • Differential Cross-sections

• Conclusion

• Acknowledgments

• References

The following sections are included:

• Introduction

• Wavepacket Dynamics and Detection

• Non-adiabatic Processes

• Role of the Ionization Continuum Electronic Channel

• Femtosecond Laser Techniques

• Techniques of Femtosecond Time-Resolved Photoelectron Spectroscopy

• Experiments

• Conclusions and New Directions

• Acknowledgments

• References

The following sections are included:

• Ultrafast Processes in Electronically Excited Molecules and Clusters

• Experimental Techniques

• Excitation Model and Time Evolution

• Analysis of Ultrafast Processes in Different Molecular Systems
  • Internal Conversion in Excited Molecular Benzene Complexes
    • Introduction
    • Internal Conversion in the Benzene Monomer and Dimer
    • Internal Conversion in C₆H₆(NH₃)_n Heteroclusters
  • Dissociation and H-Atom Transfer in Ammonia Clusters
    • Introduction
    • Results and Discussion
  • Electron Configuration Dynamics in Pyrazine
    • Introduction
    • Results and Discussion
  • Ultrafast Internal Conversion and Dissociation in Ethylene and Vinyl Chloride
    • Introduction
    • Results and Discussion
  • Intracluster Harpooning Reaction in Ba⋯FCH₃
    • Introduction
    • Results and Discussion

• Future Developments

• Acknowledgments

• References

The following sections are included:

• Introduction

• The Renner–Teller Effect in Spectroscopy
  • Structure and Predissociation of Ro-Vibronic States
    • Linear/Linear Case
    • Linear/Bent Case
    • Bent/Bent Case
    • Predissociation of Renner–Teller States

• Requirements on the Accuracy of the Electronic Structure Calculations

• Renner–Teller Spectra of Molecular Ions
  • , , COS⁺, N₂O⁺
  • 
  • H₂O⁺
  • H₂S⁺ and H₂Se⁺
  • and
  • Tetra-Atomic Ions HCCH⁺ and HBBH⁺
  • and

• Anharmonic Resonances

• Weakly Bound Triatomic Renner–Teller Ions
  • He⋯HF⁺
  • 
  • 

• On the Role of Degenerate Electronic States in Molecular Ions
  • On the Mechanism of the Energy Redistribution in the State of the HCCH⁺ Ion
  • On the Ion–Molecule Reaction and the Predissociation of the A²Σ⁺ and B²Π states of N₂O⁺
    • The a⁴Σ⁻ and b⁴Π States of N₂O⁺ and then-Interactions with the Doublet States
    • The A²Σ⁺ and B²Π States of N₂O⁺
  • The Potential Energy Functions of the Excited Electronic States of
  • Photodissociation, Charge- and Atom-Transfer Processes in Electronically Excited States of
  • Chemiluminescence in the Charge Transfer Reaction H⁺ + HCl → HCl⁺ + H
  • Isomerization of AlOH⁺
  • Structure of H₂O⁻

• Conclusion

• Acknowledgment

• References

The following sections are included:

• Introduction

• Characteristics of Two-Color ZEKE Photoelectron Spectroscopy

• Brief Survey of Two-Color Photoionization Efficiency Studies

• Techniques of Two-Color ZEKE Photoelectron Measurements

• ZEKE Photoelectron Spectra of Aromatic-Argon vdW Complexes
  • Shift in Adiabatic Ionization Potential
    • Benzene and Monosubstituted Benzenes
    • Disubstituted Benzenes
    • Naphthalene, Azulene, and Anthracene
    • Pyrimidine, Indole, and Fluorene
  • vdW Vibrations in Aromatic-Argon vdW Complexes (n = 1 and 2)
  • Structural Information
  • Dissociation Energy
  • Higher vdW Complexes and Structural Isomers

• Future Prospects

• Acknowledgments

• References

The following sections are included:

• Introduction

• Threshold Ionization Spectroscopy

• Rydberg Physics

• Mass Analyzed Threshold Ionization
  • Rydberg/Ion Separation
  • Experimental Schemes
  • Light Sources
    • Pump-probe Excitation
    • Vacuum Ultraviolet
  • MATI Studies
    • The Structure of Complexes
    • MATI Spectra
    • Rydberg State Structure
    • State Selected Ions

• Photoinduced Rydberg Ionization Spectroscopy
  • The Methods
    • Parent Ion Detection
    • Fragment Ion Detection
  • IR PIRI
  • PIRI Applications
    • Benzene
    • Substituted Benzenes
      • Phenol
      • Others

• Conclusion

• Acknowledgments

• References

The following sections are included:

• Introduction
  • Importance of Vacuum Ultraviolet Region
  • Importance of Information on Simple Diatomic Molecules
  • Photoionization and Koopmans' Theorem
  • Determination Method of Ionization Energy

• Experimental Method
  • Threshold Photoelectron Spectroscopy
  • Threshold Photoelectron Photoion Coincidence

• Results and Discussion
  • H₂
  • N₂
  • O₂
  • Homonuclear and Heteronuclear Rare-Gas Dimers
    • Homonuclear Rare-Gas Dimers
      • Ar₂
      • Kr₂ and Xe₂
    • Heteronuclear Rare-Gas Dimers
      • Potential energy curves of heteronuclear rare-gas dimers
      • ArKr
      • KrXe
      • ArXe

• Recent Developments

• Appendix
  • Harmonic Oscillator and Morse Function
  • Rydberg–Klein–Rees (RKR) Method
  • LeRoy–Bernstein Plot

• Acknowledgments

• References

The following sections are included:

• Introduction

• Photoionization and Photoelectron Studies at the ALS
  • Photoionization-Photoelectron Facility of the Chemical Dynamics Beamline
    • Optical Layout of the Chemical Dynamics Beamline
    • Performance of the Monochromator System
    • Photoion-Photoelectron Apparatus
  • Photoionization and MATI Studies
    • PIE and Stark Spectra for Ne
    • MATI Spectrum for Ne and Ar
  • Pulsed Field Ionization Photoelectron Studies
    • Demonstration of Synchrotron-based PFI-PE Studies
    • Effective Lifetime Measurements of High-n Rydberg States
    • Rotational-resolved PFI-PE bands for
    • Rotational-resolved PFI-PE Bands for
    • Satellite States of Xe⁺ at 23–25 eV
  • Threshold Photoelectron-Photoion Coincidence Study

• UV/VUV Laser Studies
  • Experimental Considerations
    • VUV-PIE and VUV-PFI-PE Measurements
    • N2P-PIE and N2P-PFI-PE Measurements
  • 
    • Stark and VUV-PIE Spectra
    • VUV-PFI-PE Spectrum
    • Vibronic Band Intensities of VUV-PFI-PE, N2P-PFI-PE, and TPE Spectra
  • CH₃SH⁺, CH₃CH₂SH⁺, and
    • Ab initio Calculations
    • N2P-PIE and N2P-PFI-PE Spectra for CH₃SH and CH₃CH₂SH
      • CH₃SH⁺
      • CH₃CH₂SH⁺
    • VUV-PFI-PE Spectra of CH3SH and CH₃CH₂SH
    • VUV-PFI-PE and N2P-PFI-PE Spectra for CH₃SCH₃

• Conclusions and Future Developments

• Acknowledgments

• References

The following sections are included:

• Introduction

• Thermal Experiments
  • Experimental Techniques
  • The H₂ Loss from Ethane Ions
    • The Energetics of H₂ Loss from Ethane Ions
    • The Kinetics of H₂ Loss from Ethane Ions
  • The H₂ Loss from Ethene Ions
    • The Kinetics of H₂ Loss from Ethene Ions

• Experiments in a Cold Cluster Beam
  • Basic Principles of KER Analysis and Calculations
  • Experimental Techniques
  • The Formation of ArCO⁺ Ions
    • Ab initio Calculations of the ArCO⁺ Ion
    • The KER Analysis
  • The Formation of Ions
    • Ab initio Calculations of the Ion
    • The KER Analysis
    • Spin and Charge Distribution in and ArCO⁺

• Experiments with State Selected Molecular Ions
  • Experimental Techniques
  • The State Selective Predissociation of HBr⁺ Ions
    • The 2 + 1 REMPI Spectrum of HBr via the f³Δ₂(ν‴ = 0) ← X¹Σ(ν″″ = 0) Transition
    • The State Selective Photodissociation of HBr⁺ via the ²Σ⁺(ν′ = 2, J′, R′) ←² Π_3/2(ν″ = 0, J″,R″) Transition
    • Lifetimes of HBr⁺ Ions in the ²Σ⁺(ν′ = 2,3 and 4) State
  • The State Selective Predissociation of HCl⁺ Ions
    • The 2+1 REMPI Spectrum of HCl via the f³Δ₂(ν‴ = 0) ← X¹Σν″″ = 0) Transition
    • The State Selective Photodissociation of HCl⁺ Ions via the ²Σ⁺(ν′ = 6, J′, R′) ←² Π_3/2(ν″ = 0, J″,R″) Transition
    • Lifetimes of HCl⁺ in the ²Σ⁺(ν′ = 6,7,8) State

• Summary and Outlook

• Acknowledgments

• References

The following sections are included:

• Introduction

• Laser Two-Photon Ionization
  • Photoionization
  • Experimental Method

• Ionization Process in Solutions
  • Time Profile of Photocurrent
  • Ionization Mechanism and Cross section

• Ionization Process on Surface
  • Characteristics of Ionization on Surface
  • Time Profile
  • Surface Concentration and Equilibrium

• Photoionization Threshold
  • Ionization Spectrum in Solution
  • Ionization Spectrum on Surface and Surface Polarity

• Analytical Applications
  • Highly-Sensitive Detection in Solution
  • Application to a Detector of Chromatography
  • Highly-Sensitive Detection on Surface
  • Applications to Environmental Samples

• Conclusion

• Acknowledgments

• References

The following sections are included:

• Introduction

• Experimental Techniques
  • Preparing Vacuum Exposed Free Liquid Surfaces
    • Liquid Surface Preparation Techniques
    • Vacuum Surface of Volatile Liquids
    • Jet Formation and Decay
  • Sampling Depth of Photoelectron Energy Spectra
    • Probing Depth of Photoelectrons
    • Electron Escape Depth

• Photoelectron Studies of Ions in Liquids
  • Pure Liquids
    • Pure Water
    • Liquid Alcohols
    • Formamide, Studied by UPS, MIES and XPS/ESCA
    • The Dielectric cavity model Gas–Liquid Shift of Photoionization Spectra
  • Solvated Ions in Aqueous Solutions
    • Halogen Salt Anions in Aqueous Solution
    • Solvation Energy and Solute Radius in a Born Model Analysis
    • Asymptotic Comparison with Negative Halogen/ Water Cluster Photodetachment and with Bulk Liquid Threshold Photoelectron Experiments
  • Concentration Depth Profile at Salt/Formamide Solution Surfaces from Angular Resolved Photoelectron Spectra
    • Potassium Octanoate in Formamide Solution
    • Distributions of TBA⁺-Ions in Subsurface Layers Studied by ARUPS

• Conclusions

• References

The following sections are included:

• Introduction

• History and Applications of Dissociative Recombination

• Ion Synchrotrons and Storage Rings

• Experimental Procedure

• Dissociative Recombination through a Crossing of Potential Curves
  • Diatomic Hydrogen Ions
  • Monohydride Ions
  • Nonhydride Diatomic Ions
    • Oxygen
    • Nitrogen
    • Nitric Oxide
    • Other Ions

• Tunneling Dissociative Recombination
  • HeH⁺
  • 

• Products of Dissociative Recombination of Polyatomic Ions

• Conclusions and Outlook

• Acknowledgments

• References

The following sections are included:

• Introduction
  • Dissociative Photodetachment Processes
  • Three-Body Dissociative Photodetachment

• Coincidence Techniques for the Study of Dissociative Photodetachment
  • Photoelectron-Photofragment Coincidence Spectrometer
  • Particle Detection
    • Wedge-and-Strip Anode
    • Multiparticle Detection with Crossed Delay Lines
  • Data Acquisition
  • Data Analysis
    • Fast Beam Photoelectron Spectroscopy
    • Two-Body Dissociation Kinematics
    • Three-Body Dissociation Kinematics
    • Photofragment Center-of-mass Differential Cross-sections
  • Coincidence Considerations

• Experimental Examples
  • Direct Dissociative Photodetachment:
    • Photoelectron-Photofragment Kinetic Energy-Correlations: N(E_T, eKE) Correlation Spectra
    • Franck–Condon Model for Product Translational and Vibrational Energy Partitioning
    • Internal Energy Spectra: Franck–Condon Model for Product Vibrational Energy Partitioning
    • Photoelectron-Photofragment Angular Correlation
    • The Electronic Structure of and Angular Distributions in Dissociative Photodetachment
    • Conclusions — Direct DPD of
  • Sequential Dissociative Photodetachment:
    • Photoelectron Spectra
    • N(E_T, eKE) Correlation Spectra
    • Dissociation Dynamics of the Low-lying Excited States of O₃
    • Conclusions — Sequential DPD of
  • Three-Body Dissociative Photodetachment:
    • Three-Body N(E_T, eKE) Correlation Spectra
    • Three-Body E_TOT Spectra
    • Conclusions — Three-Body DPD of

• Future Directions and Prospects

• Acknowledgments

• References

The following sections are included:

• Introduction
  • Photodetachment Photoelectron Spectroscopy
  • Anion-ZEKE Spectroscopy
  • Photodetachment Threshold Laws

• Experimental Principles and Details
  • Experimental Principles
  • Anion Formation of Atomic and Molecular Systems
  • Mass Separation prior to Spectroscopy
  • Laser-Induced Photodetachment
  • Electron Energy Analyzer/Zero Kinetic Energy Electron Discriminator

• Examples of Mass Selected Anion-ZEKE Spectra
  • Resolution of Anion-ZEKE Spectroscopy
  • Anion-ZEKE Spectrum of the OH Radical
  • Anion-ZEKE Spectrum of Metal Carbon Complexes: FeC₂
  • Anion-ZEKE Spectrum of Metal Oxides: FeO
  • Anion-ZEKE Spectrum of Heterogeneous Water Clusters: I⁻ (H₂O)

• Conclusion

• Acknowledgment

• References

The following sections are included:

• Introduction

• Experimental Technique
  • Pulsed Laser Vaporization Cluster Source, Mass Selection and Ion Deceleration
  • Magnetic-Bottle Time-of-Flight Photoelectron Analyzer
  • Performance: PES of Cu⁻ at 3.49, 4.66 and 6.24 eV

• Results and Discussion
  • (x = 1,2; y = 1–6)
    • CuO and CuO⁻: Excited State of CuO⁻
    • CuO₂ and : Two Isomers — Cu(O₂) and OCuO
    • CuO₃ and : Photodissociation of
    • : O₂-Complexes
    • Structure and Bonding Evolution of CuO_y (y = 1–6)
    • (y = 1–4): Sequential Oxidation and Density Functional Calculations
  • (y=1,2)
    • NiO and NiO⁻: Complicated Low-lying Electronic States of NiO
    • NiO₂ and : Two Isomers of NiO₂ – Ni(O₂) and ONiO
  • (x = 1–16; y = 1–6)
    • (y = 1–4): Sequential Oxidation of Fe
    • (y = 1–5): Sequential Oxidation of Fe₂
    • and : Sequential O Atom Chemisorption on Cluster Surfaces
    • Fe_xO⁻ (x = 1–16): O Atom Chemisorption on Iron Cluster Surfaces
  • (y = 1–4)
    • VO and VO⁻: Low-lying Electronic States of VO
    • VO₂ and
    • and
    • Electronic and Structural Evolution from VO to VO₄
  • (x = 1–4; y = 1–8)
    • TiO and TiO⁻: Low-lying States and Strong Electron Correlation Effects
    • TiO₂ and
    • 
    • (TiO₂)_n (n = 2–4): Evolution of HOMO–LUMO Gap
  • and (y = 1–5)
    • ScO and YO: Low-lying States and Strong Electron Correlation Effects
    • ScO₂ and YO₂: Two Isomers — Dioxide and O₂-Complex
    • ScO_y and YO_y (y ≥ 3) and Isomers

• Conclusions

• Acknowledgments

• References

The following sections are included:

• Introduction
  • Scope of this Chapter
  • Various Stabilities of Molecular Anions
    • Electronically Stable
    • Locally Geometrically Stable
    • Thermodynamically Stable
  • Various Mechanisms for Molecular Anions to Eject an Electron
    • Direct Photon-Initiated Detachment
    • Photon-Initiated Detachment Involving Non-Born–Oppenheimer Coupling
    • Photon-Initiated Detachment Involving Shape and Feshbach Resonances
      • Shape Resonances
      • Feshbach Resonances
    • Collision-Induced Detachment

• Direct Photodetachment
  • Time Dependent Perturbation Rate Expression
  • The Rate and Cross-Section
  • Electronic, Vibrational and Rotational Components
  • The Electronic Integral
  • Threshold Forms of Cross-Sections
  • What does One Learn from a Photodetachment Experiment?
    • Vibrational (and Maybe Rotational) Energy Levels of the Daughter Neutral
    • Transition-Region Dynamical Information
    • Identification of New Molecular Anions

• Autodetachment after Photon or Collisional Excitation
  • Detachment through Shape or Feshbach Resonances
  • Detachment through Non-Born-Oppenheimer Coupling
    • What are Non-Born–Oppenheimer Couplings?
    • The Nature of the Electronic Matrix Elements
    • A Few Examples
      • Rotational Detachment in NH⁻
      • Vibrational Detachment in Enolates
      • Collisional Detachment in OH⁻
      • Rotational Detachment in Dipole–Bound Anions

• Summary

• Acknowledgments

• References

The following sections are included:

• Introduction

• Experimental Approach
  • Preparation of the Excited States and Absorption Spectra
  • Detection of Ionization Products
  • Detection of Dissociation Products

• The Vibrational Propensity Rule

• Autoionization and Predissociation in NO

• Triatomic Molecules: HCO and NO₂

• Larger Polyatomic Molecules
  • NH₃
  • Dabco

• Summary

• Acknowledgments

• References

The following sections are included:

• Introduction
  • Electron Capture by Molecules
  • Stable Negative Ions and Temporary Negative Ions (TNIs)
  • Decomposition Pathways of Temporary Negative Ions
  • Formation and Evolution of Temporary Negative Ions (TNIs) under Aggregation
  • Overview on Previous Work

• Experimental Considerations
  • Gas-Phase Experiments: Molecules and Clusters
    • Principle and Limitation of the Method
    • Supersonic Beam and Electron Beam
    • Time-of-Flight (TOF) Analysis of Product Ions
  • Condensed Phase Experiment
  • Calibration of the Electron Energy Scale in Gas-Phase and Condensed Phase Experiments

• Results and Discussion
  • Gas-Phase Molecules
    • Dissociative Attachment to CF₃X (X = Cl, I): Structural Similar Molecules with Very Different Cross-Sections
    • Electron Attachment to Larger Molecules: C₆F₅X (X = F, Cl, Br, I), SF₆, C₆₀ and C₇₀. Competition between Dissociative and Associative Processes
    • Temperature Dependence of Dissociative Attachment Reactions
  • Gas-Phase Clusters
    • CF₃Cl and CF₃I Clusters: Formation of Relaxed Parent Anions and Inelastic Scattering prior to Electron Localization
    • C₆F₅X Clusters (X = F, Cl, Br, I): Quantitative Quenching of Chemical Fragmentation
    • Nucleophilic Displacement (S_N2) Reactions in Binary van der Waals Clusters Induced by Resonant Electron Capture
  • Adsorbed and Condensed Molecules
    • CF₃X (X = F, Cl): Desorption of Ionic Fragments via Precursor Resonances
    • Medium Enhanced Dissociative Attachment at the Surface

• Acknowledgments

• References

The following sections are included:

• Introduction

• Visualization of Electron Correlation in Doubly Excited States of Atoms
  • Configuration Mixing
  • Pauli Correlation and Visualization of Electron Correlation
  • Body-Fixed Frame Wavefunctions
  • Electron Correlations in Doubly Excited States of Atoms
  • Electron Correlation in Higher Doubly Excited States
  • Classification of Doubly Excited States
  • Ro-Vibrational Spectra of Doubly Excited States
  • The Hyperspherical Approach

• Doubly and Triply Excited States of Three-Electron Atoms
  • Introduction
  • The Hyperspherical Approach
  • Hyperspherical Adiabatic Potential Curves
  • Radial Correlations and Separations into Manifolds
  • Correlations in Doubly Excited States of Li

• Correlation in Triply Excited States of Li
  • Body-Fixed Frame Analysis of the Channel Wavefunctions
  • Rotational Excitations and Energies of 2l2l′2l″ States of Li
  • Rotational Decomposition of the Body-Fixed Frame Wavefunctions
  • Demonstration of Rotor Structure of Intrashell Triply Excited States
  • Higher Triply Excited States

• Summary and Conclusions

• Acknowledgments

• References

The following sections are included:

• Introduction

• Photoelectron Spectroscopy
  • Differential Photoionization Cross-Section
  • Two-Dimensional Time-of-Flight Spectroscopy
  • The High-Resolution Hemispherical Analyzer
  • The Electron Cylindrical Mirror Analyzer Spectrometer
  • The High-Resolution Atomic and Molecular Beamline

• Atomic Autoionization
  • Angular Distribution and R-Matrix Calculations of the Ne 2s⁻¹ → np Autoionization Resonances
  • Angular Distribution and R-Matrix Calculations of the Ar 3s⁻¹ → np Autoionization Resonances

• The Resonant Auger Process
  • Angle-Resolved , d Resonant Auger Decay
  • The 2p⁻¹4s Resonant Auger Spectra
  • The 2p⁻¹3d and 4d Resonant Auger Spectra
  • Angle-Resolved Resonant Auger Decay
  • Angle-Resolved Xe 4d_5/2 → 6p Decay under Auger Resonant Raman Conditions

• Doubly and Triply Excited States in Atoms
  • Doubly Excited States in Neon: Breakdown of LS Coupling
  • Photoelectron Spectroscopy Studies of Hollow Lithium States
    • Partial Photoionization Cross-Sections, Energies and Widths
    • Rydberg Series
    • The Lowest-Energy Doubly Hollow 3s²3p²P State

• Inner-Shell Excitation in Molecules
  • Angle-Resolved Studies of Cl 2p excitations in HCl Using an Imaging Technique
  • Evidence of a σ_u Shape Resonance in C₂H₂
  • Angular Distribution of the Sulphur 2p Photoemission in OCS: Variations Revealed by Molecular Field Splitting
  • Core Excitation in CO

• Conclusion

• Acknowledgments

• References

The following sections are included:

• Introduction

• Photon–Atom Interactions in the X-ray Regime

• Photon Scattering from Free Atoms

• Subshell-Specific Compton Scattering: Infrared Divergence

• Inelastic Scattering Probes of Electron Pair Correlation and Other Properties

• Experimental Methods for X-ray Fluorescence Spectroscopy

• X-ray Resonant Raman Scattering from Atoms

• X-ray Polarization Anisotropy of Aligned Molecules

• Nondipole X-ray Resonant Raman Scattering from Molecules

• Acknowledgments

• References

The following sections are included:

• INDEX