APPLIED SPECTROSCOPY A Compact Reference for Practitioners Edited by KIMBERLY-CLARK CORPORATION NEENAH, WI Art W. Springsteen LABSPHERE, INC. NORTH SUTTON, NH ACADEMIC PRESS San Diego London Boston New York Sydney Tokyo Toronto
Contents CONTRIBUTORS PREFACE ix xi Section 1 The Practical Basics of Spectrometry 1. Optical Spectrometers I. Introduction 4 II. Types of Spectrometers 5 III. Details of Spectrometer Components 10 IV. Properties of Spectrometers 18 References 27 Further Reading 28 2. Ultraviolet, Visible, and Near-Infrared Spectrometry I. Introduction 29 II. Instrumentation 30 III. Sampiing Considerations 36 IV. Applications 38 Further Reading 47 3. A Review of Sampiing Methods for Infrared Spectroscopy John Coates I. Introduction 50 II. General Considerations 51 III. Sample Type versus Sampiing Method 53 IV. Sampiing Method versus Sample Type 62 V. Sample Modification and/or Purification Methods 79 VI. Recommended Spectrum Acquisition, Presentation Format, and Data Manipulation Procedures 85 VII. Summary 89 References 89 V
vi < Contents 4. Spectroscopic Quantitative Analysis James H. Duckworth I. What is "Chemometrics"? 93 II. The Beer-Lambert Law 94 III. Classical Quantitation Methods 95 IV. Eigenvector Quantitation Methods 107 5. Spectroscopic Qualitative Analysis James H. Duckworth I. Discriminant Analysis 166 II. Simple Spectrum Matching Methods 168 III. Other Methods 170 IV. The Mahalanobis Distance with PCA 171 V. Coupling Mahalanobis Distance with PCA 176 Section 2 Reflectance Measurements of Solids 6. Reflectance Spectroscopy: An Overview of Classification and Techniques Art Springsteen I. Relative Specular Measurements 194 II. Absolute Specular Reflectance 198 III. Sample Preparation and Handling 202 IV. Diffuse and Total Reflectance 202 V. Integrated Sphere Measurements of Diffuse Reflectance 203 VI. Integrated Sphere Geometries 205 VII. Nonintegrating Sphere Methods 210 VIII. Diffuse/Directional Measurement of Reflectance 212 IX. Directional/Directional Diffuse Reflectance Measurements 216 X. Goniospectrophotometric Measurement of Reflectance 218 XI. Reflectance Measurement Techniques 220 References 223
CONTENTS vn 7. Spectroscopy of Solids I. Introduction 225 II. The Physics of Light Interaction with Solid Materials 226 III. Devices Used for Spectroscopy of Solids 229 IV. Applications for Spectroscopy of Solids 232 V. Conclusions 245 References 245 8. Standards for Reflectance Measurements Art Springsteen I. Specular Standards 249 II. Diffuse Reflectance Standards 251 III. Mid-Infrared Diffuse High-Reflectance Standards 258 IV. Gray Scale Standards for UV-VIS-NIR 259 V. Mid-Infrared Gray Scale Standards 261 VI. Color Standards 261 VII. Wavelength Calibration Standards 262 References 265 9. Reflectance Measurements of Diffusing Surfaces Using Conic Mirror Reflectometers Keith A. Snail and Leonard M. Hanssen I. Introduction 269 II. Terminology 271 III. Historical Overview 273 IV. Measurement Geometries 276 V. Sources of Error 278 VI. Summary and Conclusions 296 References 296 10. Bidirectional Reflectance Distribution Function as a Measure of Optica! Scatter S. H. C. P. McCall I. Introduction: Significance and Use of the Bidirectional Reflectance Distribution Function 299 II. Terminology and Definition of BRDF 302
Vlll Contents III. Interpreting BRDF Light Scatter Measurements 308 IV. Summary 321 Appendix 321 References 323 Additional Sources 324 Section 3 Practica! Application of Spectroscopic Measurement 11. Selecting a Spectroscopic Method by Industrial Application Emil W. Ciurczak I. TheProcess 329 II. The Product 333 III. The Measurement Procedure 336 IV. Summary and Conclusions 341 References 342 12. Color and Solar Transmittance Measurements J. Murray Stewart I. Introduction 344 II. Current Color Spectrophotometer Principles and Geometries 346 III. Instrument Applications 352 IV. Measurement Techniques 359 V. Mathematical Considerations 365 VI. Pitfalls: User Techniques 374 VII. Limitations: Instruments and Techniques 377 VIII. Advances Needed 381 References 383 13. Optica! Spectroscopy of New Materials Susan White I. Background 389 II. Current State of the Art 390
CONTENTS ix III. Current Applications 391 IV. Pitfalls of Techniques for Basic Users 393 V. Limitations of Current Instrumentation and Techniques 395 VI. Advances Needed in the Field 396 References 396 14. Spectroscopy of Ceramics James F. Cordaro I. Introduction 399 II. Scattered Light and Its Relationship to Reflectance of Ceramics 400 III. Reflected Light from Opaque Ceramics 405 IV. Transmitted Light through Ceramic Crystals 413 V. Mechanisms of Optical Absorption in Ceramics 415 References 421 15. Spectroscopy Using Flowing Systems for Chemical, Pharmaceutical, and Biological Applications Emil W. Ciurczak I. Defining the Sample/System 423 II. Choosing the Appropriate Measuring Instrumentation 426 III. Applications 431 IV. Conclusion 435 References 435 16. Textile Application of Molecular Spectroscopy Subhas Ghosh > I. Introduction 437 II. Textile Test Specimens 438 III. Applications in Greige Manufacturing Processes 438 IV. Thermal History of Synthetic Fibers 444 V. Fabric Finishing Application: Durable Press Resin on Fabrics 446 VI. Application of Infrared Spectroscopy in Textiles 450 References 457
x Contents 17. Solar Measurements J. Murray Stewart I. Introduction 459 II. Spectrophotometer: Principles and Geometries 461 III. Instrument Applications 466 IV. Measurement Techniques 474 V. Mathematical Considerations 478 VI. Basic User Technique Pitfalls 481 VII. Limitations 486 VIII. Advances Needed 487 References 489 Appendix A: Sources, Detectors, and Window Materials for UV-VIS, NIR, and IR Spectroscopy 493 Appendix B: Practices of Data Preprocessing for Optical Spectrophotometry 497 Appendix C: Infrared Microspectroscopy 507 Appendix D: Diffuse Transmittance and Optical Geometry 513 Appendix E: Dichroic Measurements of Polymer Films Using Infrared Spectrometry. 525 INDEX 531