Advances in Multi-Photon Processes and Spectroscopy

The following sections are included:

• PREFACE

• CONTENTS

The following sections are included:

• Introduction, Historical Background, Basic Multiphoton Processes

• Two-Photon Processes

• Higher than Second-Order Ionization Processes

• Laser-Induced Shifts and Widths

• Coherent Strong-Field Effects

• Light Fluctuation Effects in Multiphoton Processes

• Time and Bandwidth Effects

• Dressed Free Electron Interactions

• Acknowledgements

• References

The following sections are included:

• Introduction

• Multiphoton Ionization
  • Review
  • MPI Spectra of Some Polyatomic Molecules
    • Two Caged Amines: 1–Azabicyclo[2,2,2]octane (ABCO) and 1,4–Diazabicyclo[2,2,2]octane (DABCO)
    • Pyrazine and Pyridine
    • Alkyl Iodides
  • MPI Polarization Studies of Two-Photon Transitions of Polyatomic Molecules
  • Lifetime Determination by Two-Color MPI Techniques
  • Ionization Potential Determination by MPI
  • Picosecond Pulsewidth Determination by MPI

• Multiphoton Ionization Dissociation Mass Spectrometry (MPIDMS)
  • Historical Development
  • Theoretical Development
    • MPID Mechanisms
    • Statistical Approaches
      • Maximum Entropy Model
      • Products Phase Space Model
      • Ladder Switching Model
    • Concluding Remarks on the Statistical Approaches
    • Results on Benzaldehyde and Phenol by the Phase Space Model
  • Techniques and Results
    • The Importance of Neutral Fragments: Variable Repelling Voltage Techniques
    • Wavelength and Power Dependence Studies of Benzaldehyde
      • With Nanosecond Pulsed Lasers
      • With Picosecond Pulsed Lasers
    • Dynamics Prior to Dissociation with Two-Color Experiments
      • Nanosecond Results: Phenol
      • On the Picosecond Timescale: 2,4-Hexadiyne

• ACKNOWLEDGEMENT

• References

Various theoretical approaches to laser-induced molecular dynamics in the context of multiphoton processes are reviewed. The presentation is divided into two general categories: gas-phase processes and surface processes. Within the first category, unimolecular dynamics and molecular collisions are addressed. Within the second category, energy flow in adspecies-surface systems is examined, and laser applications to surface chemistry are discussed.

The following sections are included:

• Introduction

• A brief review of multiphoton absorption theory
  • Coherent processes
  • Incoherent Processes
  • Dephasing Processes

• Multiphoton absorption processes
  • Virtual States as Intermediates
    • Monocolor excitation
    • Optical-optical double resonance
  • Bound States as Intermediates
  • Dissociative states as intermediates

• Multiphoton Photochemistry
  • Photodynamics
  • Reaction Dynamics
    • Multiphoton Process as a Photolysis method
    • Multiphoton Processes as a Detection Method

• Concluding Remarks

• REFERENCES

The following sections are included:

• INTRODUCTION

• NITROGEN OXIDES
  • Introduction
  • Nitric Oxide Dimers
  • Sym- and Asym- Dinitrogen Trioxides
  • Other Species and Summary

• INORGANIC HALIDE SYSTEMS
  • Halo-Bismuthates and Antimonates
  • Ions
  • Polyhalides

• POTENTIAL ENERGY FUNCTIONS AND SURFACES
  • Introduction
  • Ring Molecules
    • Cyclopentene
    • 1,3-disilacyclobutane
    • 3-phospholene and 2-phospholene
    • Bicyclic molecules
    • Other molecules
  • Molecular Torsions

• A PHASE DEPENDENT STUDY OF 1,3-DISILACYCLOBUTANE

• RAMAN DIFFERENCE SPECTROSCOPY
  • Methods and Theory
  • Aqueous Nitrate Solutions
  • Isotopic Dilution Studies

• CONCLUSION

• Acknowledgements

• References

We review our recent work on the development of the master equation approach to the theory of laser-stimulated surface processes. This approach focusses attention on the competition between the various possible rate processes involved. We first derive general reduced master equations for a system subjected to an external time-dependent field and then apply them to various surface processes. We consider both processes involving one electronic state (IR laser-stimulated desorption and diffusion, for example) and processes involving two electronic states (UV/visible laser-stimulated processes). The theoretical results on IR laser-stimulated desorption are used to analyze experimental results on the CO₂ laser-stimulated desorption of pyridine from Ag surfaces.