Photoionization and Photo-Induced Processes in Mass Spectrometry Fundamentals and Applications

Provides comprehensive coverage of laser-induced ionization processes for mass spectrometry analysis

Drawing on the expertise of the leading academic and industrial research groups involved in the development of photoionization methods for mass spectrometry, this reference for analytical scientists covers both the theory and current applications of photo-induced ionization processes. It places widely used techniques such as MALDI side by side with more specialist approaches such as REMPI and RIMS, and discusses leading edge developments in ultrashort laser pulse desorption, to give readers a complete picture of the state of the technology.

Photoionization and Photo-Induced Processes in Mass Spectrometry: Fundamentals and Applications starts with a complete overview of the fundamentals of the technique, covering the basics of the gas phase ionization as well as those of laser desorption and ablation, pulse photoionization, and single particle ionization. Numerous application examples from different analytical fields are described that showcase the power and the wide scope of photo ionization in mass spectrometry.

• The first general reference book on photoionization techniques for mass spectrometry
• Examines technologies and applications of gas phase resonance-enhanced multiphoton ionization mass spectrometry (REMPI-MS) and gas phase resonance ionization mass spectrometry (RIMS)
• Provides complete coverage of popular techniques like MALDI
• Discusses the current and potential applications of each technology, focusing on process and environmental analysis

Photoionization and Photo-Induced Processes in Mass Spectrometry: Fundamentals and Applications is an excellent book for spectroscopists, analytical chemists, photochemists, physical chemists, and laser specialists.

Preface xi

1 Fundamentals and Mechanisms of Vacuum Photoionization 1
Johannes Passig, Ralf Zimmermann, and Thomas Fennel

1.1 Preface 1

1.2 Light 2

1.3 Photoabsorption 5

1.3.1 Transitions in First Order Perturbation Theory 5

1.3.2 Perturbation Theory 6

1.3.3 Absorption 7

1.3.4 Dipole Approximation 9

1.3.5 Selection Rules 11

1.3.6 Electronic Line Width and Lifetime 11

1.3.7 Electronic Transitions of Molecules 13

1.3.8 Single-photon Ionization (SPI) 15

References 20

2 Fundamentals and Mechanisms of Resonance-Enhanced Multiphoton Ionization (REMPI) in Vacuum and its Application in Molecular Spectroscopy 23
Ulrich Boesl and Ralf Zimmermann

2.1 Introductory Remarks 23

2.2 Beginnings of REMPI 25

2.3 Principle of REMPI: Rate Equations and Quantification of Detection Efficiency 29

2.3.1 Rate Equations 29

2.3.2 Quantification of the REMPI Detection Efficiency 31

2.3.3 Special Situations and Problems in REMPI Processes and Countermeasures 33

2.3.3.1 Situation (A): Too energetic ionization threshold 34

2.3.3.2 Situation (B): Too energetic intermediate state 35

2.3.3.3 Situation (C): Too small FC-factors 36

2.3.3.4 Situation (D): Too fast relaxation of intermediate state 37

2.4 REMPI and Dissociation 40

2.5 Application of REMPI for Optical Spectroscopy 45

2.5.1 Effusive Gas Beam Molecules at Room or Elevated Temperature: REMPI Spectra with Medium Optical Selectivity 45

2.5.2 Supersonic Gas Beams for Cold Molecules: REMPI Spectra with High Optical Selectivity for Discrimination of Structural Isomers and Spectroscopic Studies on the Transition State 48

2.5.2.1 REMPI Spectroscopy of Jet-Cooled Biphenylene 50

2.5.2.2 REMPI Spectroscopy of Jet-Cooled Dibenzo-p-dioxin and Its Derivatives as well as of [2,2]-Paracyclophane 61

2.5.3 Supersonic Gas Beams for Cold Molecules: REMPI Spectra with High Optical Selectivity for Discrimination of Isotopomers 67

2.5.4 Chiral Molecules: Discrimination of Enantiomers by Enantioselective REMPI Spectroscopy 69

2.5.5 Advanced Photoelectron Spectroscopy Based on REMPI: The PES, TPES, ZEKE, MATI, Anion-PES, and Anion-ZEKE Approaches 72

References 79

3 Analytical Application of Single-Photon Ionization Mass Spectrometry (SPI-MS) 89
Thorsten Streibel, Hendryk Czech, and Ralf Zimmermann

3.1 VUV Light Sources 89

3.2 Lamp-Based VUV Light Sources 90

3.3 Laser-Based VUV Light Sources 92

3.4 Mass Spectrometry with Lamp or Laser-Based VUV Light Sources 94

3.5 On-line Analysis of Complex Mixtures by Single-Photon Ionization (SPI) Mass Spectrometry 95

3.6 SPI-MS in Hyphenated Applications 107

3.7 Ambient Monitoring 117

3.8 Commercial Solutions 118

References 119

4 Analytical Application of Resonance-Enhanced Multiphoton Ionization Mass Spectrometry (REMPI-MS) 125
Thorsten Streibel, Ulrich Boesl, and Ralf Zimmermann

4.1 Investigation of Model Flames 129

4.2 Applications to Internal Combustion Engines 130

4.3 Monitoring Combustion Process Emissions in an Industrial Environment 135

4.4 Further Applications of REMPI Mass Spectrometry 138

4.5 REMPI-MS in Hyphenated Analytical Systems 142

4.6 Commercial REMPI-MS Solutions and Applications 150

References 152

5 Probing Chemistry at Vacuum Ultraviolet Synchrotron Light Sources 159
Kevin R. Wilson and Fei Qi

5.1 Introduction 159

5.2 Combustion Chemistry 162

5.2.1 Pyrolysis in Flow Reactor 163

5.2.2 Jet-Stirred Reactor Oxidation 166

5.2.3 Premixed Flames 167

5.2.3.1 Low-Pressure Laminar Premixed Flame 167

5.2.3.2 Atmospheric Pressure Laminar Premixed Flame 171

5.2.4 Coflow Diffusion Flame 173

5.2.5 Biomass/Coal Pyrolysis 174

5.3 Isomer-Resolved Studies of Elementary Chemical Reactions 176

5.3.1 Multiplexed Chemical Kinetics Photoionization Mass Spectrometer 177

5.3.2 Shock Tube Kinetics 179

5.3.3 Pyrolysis Reactors 180

5.3.3.1 Bimolecular Kinetics 181

5.3.3.2 Unimolecular Kinetics 181

5.3.4 Low-Temperature Elementary Reactions in a Pulsed Laval Nozzle 182

5.4 Summary 186

5.4.1 Atmospheric Aerosol Chemistry 188

5.4.1.1 Aerosol Mass Spectrometry 189

5.4.1.2 Gas Chromatography and SVUV Photoionization Mass Spectrometry 195

5.4.2 Future Outlook 202

Acknowledgments 203

References 203

6 Resonance Ionization Mass Spectrometry (RIMS): Fundamentals and Applications Including Secondary Neutral Mass Spectrometry 215
Michael Savina and Reto Trappitsch

6.1 Introduction 215

6.2 Resonance Ionization Fundamentals 217

6.2.1 Laser Spectroscopy 217

6.2.2 Selection Rules 220

6.2.3 Odd–Even Effect 222

6.3 Reduction to Practice 224

6.3.1 Laser Selection 224

6.3.2 Mass Spectrometer Selection 225

6.3.3 Laser Overlap 229

6.4 Applications 230

6.4.1 Useful Yield and Abundance Sensitivity 231

6.4.2 Stardust Grains 234

6.4.3 Multielement Analysis 236

6.4.4 Electronic Processes During Vaporization 238

6.5 Resources 240

References 241

7 Ultrashort Pulse Photoionization for Femtosecond Laser Mass Spectrometry 245
Cornelius L. Pieterse, Jason M. Gross, and Luke Hanley

7.1 Introduction 245

7.2 Mechanisms of Ultrashort Pulse Photoionization 246

7.3 Studies of Amino Acids, Dipeptides, and C60 Leading to Advanced SFI Models 249

7.4 Volumetric Intensity Dependence and Multiply Charged Ions 251

7.5 Direct and Gas Chromatography-Coupled Analysis of Explosives 253

7.6 Gas Chromatography-Coupled Analysis of Polyaromatic Hydrocarbons, Pesticides, and Fragrances 255

7.7 Laser Secondary Neutral Mass Spectrometry 256

7.8 Conclusions 259

Acknowledgments 260

Disclosure Statement 260

References 261

8 Photoionization at Elevated or Atmospheric Pressure: Applications of APPI and LPPI 267
Tiina J. Kauppila and Jack Syage

8.1 Introduction 267

8.2 Atmospheric Pressure Photoionization 267

8.2.1 Atmospheric Pressure Photoionization Ion Source 267

8.2.2 General Principles of Atmospheric Pressure Photoionization 268

8.2.2.1 Ionization Mechanism in Positive Ion APPI 268

8.2.2.2 Effect of the Dopant 270

8.2.2.3 Ionization Mechanism in Negative Ion APPI 271

8.2.3 APPI in Liquid Chromatography Mass Spectrometry 272

8.2.4 APPI in Gas Chromatography Mass Spectrometry 274

8.2.5 APPI As an Interface for Capillary Electrophoresis Mass Spectrometry 277

8.2.6 APPI in Multimode Ion Sources 278

8.2.7 Ambient Mass Spectrometry Utilizing Photoionization 278

8.3 Low-Pressure Photoionization (LPPI) 279

8.4 Applications of APPI and LPPI 281

8.4.1 Drugs, Pharmaceuticals, and Metabolites 281

8.4.2 Steroids 288

8.4.3 Other Endogenic Compounds 288

8.4.4 Plant Research 289

8.4.5 Environmental Monitoring 289

8.4.6 Oil Analysis 291

8.4.7 Food Analysis 291

8.5 Conclusions 292

Acknowledgments 292

References 292

9 Fundamentals of Laser Desorption Ionization 305
Fabrizio Donnarumma, Kermit K. Murray, and Luke Hanley

9.1 Introduction 305

9.2 Experimental and Computational Parameters and Observables 306

9.3 General Mechanistic Considerations 307

9.4 Laser-Induced Thermal or Acoustic Desorption of Neutrals from Metal Surfaces 307

9.5 Molecular Resonantly Enhanced Desorption: UV-MALDI and IR-LA 309

9.5.1 MALDI with UV Lasers 310

9.5.2 Nanosecond to Picosecond IR Laser Ablation 313

9.6 Nanophotonic Desorption 314

9.7 Femtosecond Laser Ablation 315

9.8 Internal Energy Transferred by LDI and Supersonic Cooling 317

9.9 Conclusions 318

Acknowledgments 319

Disclosure Statement 319

References 319

10 Applications of Laser Desorption Ionization and Laser Desorption/Ablation with Postionization 327
Yeni P. Yung, Fabrizio Donnarumma, Kermit K. Murray, and Luke Hanley

10.1 Nature of Samples and Information to be Gained from Laser Desorption and Laser Ablation Mass Spectrometry 327

10.2 Laser Ablation and Laser Desorption Ionization MS for Elemental Analysis 328

10.3 Nonimaging MALDI-MS for Molecular Analysis 329

10.3.1 Qualitative and Quantitative Performance for Different Types of Analytes 329

10.3.2 Peptides, Proteins, Lipids, and Sugars 330

10.3.3 DNA and RNA 330

10.3.4 Polymers 331

10.4 MALDI-MS Imaging for Molecular Analyses 332

10.5 Example of Standard MALDI-MS vs. Imaging Mode: Pseudomonas aeruginosa 333

10.6 MALDI Alternatives: Matrix Free, Ambient, Nanostructure Induced, and High Energy 335

10.7 Molecular LD/LA-MS Beyond Nanosecond UV Lasers 336

10.8 Laser, Electrospray, and Other Postionization of Plumes Formed by LD/LA 337

10.8.1 LDPI-MS: Laser Desorption Postionization of Neutrals in Vacuum 337

10.8.2 Postionization Coupled to LD/LA at Elevated Pressures 340

10.9 Laser Ablation Sampling for Solid or Liquid Collection 341

10.9.1 Laser Ablation Sampling with Online MS Analysis 342

10.9.2 Laser Ablation Sampling with Off-line Analysis 343

10.10 Conclusions 344

Acknowledgments 345

Disclosure Statement 345

References 345

11 Laser Ionization in Single-Particle Mass Spectrometry 359
Johannes Passig and Ralf Zimmermann

11.1 Relevance of Atmospheric Aerosols for Climate and Health –The Single-particle Perspective 359

11.2 Analysis of Individual Particles by Laser Ionization MS – Historical Development and Basic Principle 362

11.3 Ionization in Single-Particle Mass Spectrometry: Laser Desorption/Ionization (LDI) 365

11.3.1 Single-Particle LDI – The Physical Framework 366

11.3.2 Laser Light Sources for LDI 371

11.3.3 Chemical Quantification Approaches for LDI 372

11.4 Ionization in SPMS: Laser Photoionization of Previously Desorbed Species 373

11.5 Instrumental Realizations 381

11.5.1 Mass Analyzers 381

11.5.2 Aerosol Inlet 383

11.5.3 Particle Sizing 384

11.6 Data Evaluation 386

11.7 Applications 387

11.7.1 Ambient Aerosols in Urban and Densely Populated Areas 387

11.7.2 Ambient Aerosols in Rural and Marine Environments 388

11.7.3 Aircraft-Based Studies 389

11.7.4 In Situ Characterization of Cloud and Ice Condensation Nuclei 389

11.7.5 Focus on Organic Compounds 390

11.7.6 Bioaerosols 392

11.7.7 Combustion Aerosols 392

11.8 Commercial Laser Ionization Single-Particle Mass Spectrometry Systems 393

References 394

Index 413

Ralf Zimmermann, PhD, is full professor for Analytical Chemistry at University of Rostock (Germany) and director of the joint mass spectrometry center of University of Rostock and the Helmholtz Zentrum München. His research interests include mass spectrometry instrumentation, the analysis of complex molecular system and biomedical analysis.

Luke Hanley, PhD, is a LAS Distinguished Professor in the Department of Chemistry at the University of Illinois at Chicago. His research interests include the development of laser ablation and photoionization for mass spectrometry imaging in microbiology, materials science, and geology.