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THE ELECTRON CAPTURE DETECTOR AND THE STUDY OF REACTIONS WITH THERMAL ELECTRONS

THE ELECTRON CAPTURE DETECTOR AND THE STUDY OF REACTIONS WITH THERMAL ELECTRONS

E. C. M. CHEN

E. S. D. CHEN

A JOHN WILEY & SONS, INC., PUBLICATION

Copyright # 2004 by John Wiley & Sons, Inc. All rights reserved.

Published by John Wiley & Sons, Inc., Hoboken, New Jersey.

Published simultaneously in Canada.

No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400, fax 978-646-8600, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008.

Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages.

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Library of Congress Cataloging-in-Publication Data:

Chen, E. C. M.

The electron capture detector and the study of reactions with thermal electrons /

E.C. M. Chen, E. S. D. Chen. p. cm.

Includes bibliographical references and index.

ISBN 0-471-32622-4 (Cloth)

1. Gas chromatography. 2. Electrons–Capture. I. Chen, E. S. D. II. Title. QD79.C45 C49 2004

5430 .85–dc22

2003023101

Printed in the United States of America

 

10

9

8

7

6

5

4

3

2

1

This book is dedicated to Professor Wayne E. Wenthworth who made it possible for the authors to become scientists. Without him the work in this book could not have been accomplished.

We also recognize the contributions of Dr. James. E. Lovelock, the inventor of the electron capture detector.

CONTENTS

FOREWORD

 

xiii

PREFACE

 

xv

1. Scope and History of the Electron

1

1.1

General Objectives and Organization

1

1.2

General Scope

2

1.3

History of the Electron

4

References

 

6

2. Definitions, Nomenclature, Reactions, and Equations

8

2.1

Introduction

8

2.2

Definition of Kinetic and Energetic Terms

8

2.3

Additional Gas Phase Ionic Reactions

15

2.4

Electron Affinities from Solution Data

16

2.5

Semi-Empirical Calculations of Energetic Quantities

17

2.6

Herschbach Ionic Morse Potential Energy Curves

18

2.7

Summary

19

References

 

20

3. Thermal Electron Reactions at the University of Houston

22

3.1

General Introduction

22

3.2

The First Half-Century, 1900 to 1950

23

3.3

Fundamental Discovery, 1950 to 1960

25

3.4

General Accomplishments, 1960 to 1970

27

 

3.4.1

Introduction

27

 

3.4.2

The Wentworth Group

28

 

3.4.3

Stable Negative-Ion Formation

28

 

3.4.4

Dissociative Thermal Electron Attachment

33

 

3.4.5

Nonlinear Least Squares

35

3.5Milestones in the Wentworth Laboratory and Complementary

Methods, 1970 to 1980

37

3.6Negative-Ion Mass Spectrometry and Morse Potential Energy

Curves, 1980 to 1990

40

3.7 Experimental and Theoretical Milestones, 1990 to 2000

41

vii

viii

CONTENTS

 

3.8

Summary of Contributions at the University of Houston

42

References

43

4. Theoretical Basis of the Experimental Tools

47

4.1

Introduction

47

4.2

The Kinetic Model of the ECD and NIMS

47

4.3

Nondissociative Electron Capture

50

4.4

Dissociative Electron Attachment

59

4.5

Electron Affinities and Half-Wave Reduction Potentials

64

4.6Electron Affinities and Ionization Potentials

 

of Aromatic Hydrocarbons

66

4.7

Electron Affinities and Charge Transfer Complex Energies

67

4.8

Summary

71

References

 

73

5. Experimental Procedures and Data Reduction

75

5.1

Introduction

75

5.2

Experimental ECD and NICI Procedures

76

5.3

Reduction of ECD Data to Fundamental Properties

85

 

5.3.1

Introduction

85

 

5.3.2

Acetophenone and Benzaldehyde

86

 

5.3.3 Benzanthracene, Benz[a]pyrene, and 1-Naphthaldehyde

87

 

5.3.4

Carbon Disulfide

89

 

5.3.5

Nitromethane

90

 

5.3.6 Consolidation of Electron Affinities for Molecular Oxygen

91

5.4

Reduction of Negative-Ion Mass Spectral Data

93

5.5

Precision and Accuracy

96

5.6

Evaluation of Experimental Results

97

5.7

Summary

101

References

 

101

6. Complementary Experimental and Theoretical Procedures

103

6.1

Introduction

103

6.2

Equilibrium Methods for Determining Electron Affinities

105

6.3

Photon Techniques

110

6.4

Thermal Charge Transfer Methods

116

6.5

Electron and Particle Beam Techniques

121

6.6

Condensed Phase Measurements of Electron Affinities

124

6.7

Complementary Theoretical Calculations

125

 

6.7.1

Atomic Electron Affinities

126

 

6.7.2

Polyatomic Molecules

128

6.8

Rate Constants for Attachment, Detachment, and Recombination

132

 

CONTENTS

ix

6.9

Summary

134

References

134

7. Consolidating Experimental, Theoretical, and Empirical Data

139

7.1

Introduction

139

7.2

Semi-Empirical Quantum Mechanical Calculations

140

7.3

Morse Potential Energy Curves

150

 

7.3.1 Classification of Negative-Ion Morse Potentials

151

 

7.3.2 The Negative-Ion States of H2

153

 

7.3.3 The Negative-Ion States of I2

156

 

7.3.4 The Negative-Ion States of Benzene and Naphthalene

157

7.4

Empirical Correlations

161

7.5

Summary

165

References

166

8. Selection, Assignment, and Correlations of Atomic

 

Electron Affinities

168

8.1

Introduction

168

8.2

Evaluation of Atomic Electron Affinities

169

8.3

Mulliken Electronegativities

178

8.4

Electron Affinities of Atomic Clusters

184

8.5

Summary

189

References

190

9. Diatomic and Triatomic Molecules and Sulfur Fluorides

193

9.1

Introduction

193

9.2

Diatomic Molecules

194

9.2.1Electron Affinities and Periodic Trends of

Homonuclear Diatomic Molecules

194

9.2.2Electron Affinities and Morse Potential Energy Curves:

Group VII Diatomic Molecules and Anions

197

9.2.3Electron Affinities and Morse Potential Energy Curves:

Group VI Diatomic Molecules and Anions

205

9.2.4Electron Affinities and Morse Potential Energy Curves: Group IA and IB Homonuclear Diatomic Molecules

and Anions

209

9.2.5Electron Affinities and Morse Potential Energy Curves:

NO and NO( )

214

9.3 Triatomic Molecules and Anions

216

9.4Electron Affinities and Morse Potential Energy Curves:

Sulfur Fluorides and Anions

224

9.5 Summary

229

References

229

x

CONTENTS

 

10. Negative Ions of Organic Molecules

234

 

10.1

Introduction

234

 

10.2

Electron Affinities and Potential Energy Curves for

 

 

 

Nitrobenzene and Nitromethane

235

10.3Electron Affinities Determined Using the Magnetron, Alkali Metal Beam, Photon, and Collisional

 

Ionization Methods

238

 

10.3.1 Electron Affinities Determined Using the

 

 

 

Magnetron Method

238

 

10.3.2 Electron Affinities Determined Using the

 

 

 

AMB Method

240

 

10.3.3 Electron Affinities Determined Using

 

 

 

Photon Methods

241

 

10.3.4 Electron Affinities Determined Using Collisional

 

 

 

Ionization Methods

243

10.4

Electron Affinities Determined Using the ECD, NIMS,

 

 

and TCT Methods

244

 

10.4.1 Electron Affinities of Aromatic Hydrocarbons

 

 

 

by the ECD Method

244

 

10.4.2 Electron Affinities of Organic Carbonyl Compounds

 

 

 

by the ECD Method

246

 

10.4.3 Electron Affinities of Organic Nitro Compounds

 

 

 

the ECD and TCT Methods

253

10.5

Electron Affinities of Charge Transfer Complex Acceptors

257

10.6

Substituent Effect

261

10.7

Summary

263

References

 

263

11. Thermal Electrons and Environmental Pollutants

266

11.1

Introduction

266

11.2

Alkyl Halides

267

 

11.2.1

Morse Potential Energy Curves

267

 

11.2.2

Experimental Activation Energies

269

 

11.2.3

Alkyl Fluorocompounds

272

 

11.2.4 Electron Affinities of the Alkyl Halides

274

11.3

Aromatic Halides

276

 

11.3.1 Electron Affinities of Fluoroand Chlorobenzenes

276

 

11.3.2 Electron Affinities from Reduction Potentials

 

 

 

and CURES-EC

283

 

11.3.3 Negative-Ion Mass Spectra and Electron Affinities

284

11.4

Negative-Ion Mass Spectrometry

287

11.5

Calculation of the ECD and NIMS Temperature Dependence

291

 

 

 

 

CONTENTS

xi

 

11.6

Summary

 

293

 

References

 

 

293

12.

Biologically Significant Molecules

296

 

12.1

Introduction

 

296

 

12.2

Electron Affinities of Purines and Pyrimidines

299

 

 

12.2.1 Predictions of Electron Affinities

299

 

 

12.2.2 Electron Affinities from Reduction Potentials

300

 

 

12.2.3 Gas Phase Measurements of Electron Affinities

302

 

 

12.2.4

Theoretical Electron Affinities

305

 

12.3

Electron Affinities of Biological Molecules from

 

 

 

Reduction Potentials

307

 

12.4

Gas Phase Acidities of Nucleic Acids

310

 

12.5

Morse Potential Energy Curves for Thymine and Cytosine

311

 

12.6

Gas Phase Acidities and Electron Affinities of the Amino Acids

315

 

12.7

The Calculation of the ECD and NIMS Temperature

 

 

 

Dependence

 

316

 

12.8

Electron Affinities of AT AU and GC

318

 

12.9

Radiation Damage in DNA

320

 

12.10

Summary

 

326

 

References

 

 

327

APPENDICES

 

 

329

I Glossary of Terms, Acronyms, and Symbols

331

II Structures of Organic Molecules

336

III

General Least Squares

339

IV

Tables of Evaluated Electron Affinities

349

 

Table A1.1

Atoms

 

349

 

Table A1.2 Main Group Homonuclear Diatomic Molecules

351

 

References

 

 

352

 

Table A2.1 and A2.2

CH Molecules

355

 

References

 

 

357

 

Table A2.3 and A2.4

CHX Molecules

357

 

References

 

 

359

 

Table A3.1 and A3.2

CHNX Molecules

360

 

References

 

 

361

 

Table A4.1 and A4.2

CHO Molecules

362

 

Table A4.3 and A4.4

CHOX Molecules

366

xii

CONTENTS

 

 

 

References

 

369

 

Table A5.1 and A5.2

CHON Molecules

370

 

Table A5.3 and A5.4

CHONX Molecules

375

 

References

 

376

 

Table A6.1 Bergman Dewar set

377

 

Table A6.2 Values Different from NIST Values

 

 

(from Tables A2.1 to A5.4)

378

 

Table A6.3 Unpublished or Updated Gas Phase Values not

 

 

in NIST Tables

380

 

Table A6.4 Values for Adenine, Guanine, Cytosine, Uracil,

 

 

Thymine, and Their Hydrates

382

 

Table A6.5 Values for Charge Transfer Complex Acceptors

 

 

not in NIST Tables

382

 

Table A6.6 Values for Chlorinated Hydrocarbons from

 

 

Reduction Potentials and CURES-EC

383

 

Table A6.7 Values for Biological Compounds from

 

 

Reduction Potentials

383

AUTHOR INDEX

 

387

SUBJECT INDEX

 

395