TABLE OF CONTENTS
1.0 Introduction........................................................... 1
1.1 Rationale for use ............................................. 1
1.2 History and Basic Idea of PAS ................................. 1
1.3 Controllable Sampling Depth ................................... 3
1.4 Practical Uses of Controllable Sampling Depth ................. 3
2.0 Signal Generation Theory and Data Analysis Treatments ................. 5
2.1 Signal Generation Model - Introduction ........................ 5
2.2 Photoacoustic Signal Magnitude ................................ 5
2.3 Photoacoustic Signal Phase .................................... 8
2.4 Photoacoustic Signal Saturation ............................... 8
2.5 Sampling Depth ................................................ 11
2.6 Interpretation of Photoacoustic Signal Phase Data ............. 12
3.0 Instrumentation ....................................................... 16
3.1 Photoacoustic Detector ........................................ 16
3.1.1 Detector Description .................................... 16
3.1.1.1 Availability ...................................... 16
3.1.1.2 Design. ........................................... 17
3.1.1.3 Spectral Range. ................................... 17
3.1.1.4 Detector Optics. .................................. 17
3.1.2 Detector Installation ................................... 18
3.1.2.1 Mounting .......................................... 18
3.1.2.2 Electrical connections ............................ 18
3.1.2.3 Purge Connection for Sample Chamber ............... 18
3.1.2.4 Purged Optical Path ............................... 18
3.1.3 Detector Operation ...................................... 18
3.1.3.1 Sample Handling ................................... 18
3.1.3.2 Control of H2O and CO2 Evolution from Samples ..... 19
3.1.3.3 Detector Sample Chamber Purging ................... 19
3.1.3.4 Spectrum Normalization ............................ 20
3.1.3.5 Gain Switch Setting ............................... 20
3.1.3.6 System Checks ..................................... 21
3.1.3.7 Specialized Sampling Options ...................... 21
3.2 FTIR Spectrometer ............................................. 21
3.2.1 FTIR Operating Parameters ............................... 21
3.2.2 Modulation Frequency .................................... 22
3.2.2.1 Continuous Scan Mode Modulation ................... 23
3.2.2.2 Phase Modulation Mode ............................. 24
3.2.3 Data Handling ........................................... 26
4.0 Applications .......................................................... 27
4.1 Introduction .................................................. 27
4.2 Rapid Identification of Polymers for Recycling ................ 27
4.3 Quantitative Analysis of Major and Minor Concentrations of
Additives in Paper Products ................................... 27
4.4 Analysis of Aqueous Sludges with Soluble and Insolube Species . 30
4.5 Quantization of CaCO3 Residual in Lime ........................ 33
4.6 Determining Surface or Bulk Character of Polymer Additives .... 34
4.7 Fluorination of Polyethylene .................................. 36
4.8 Chemical Surface Treatment of Polystyrene Spheres ............. 37
4.9 Enhanced Surface Specificity by Linearization of
FTIR-PAS Spectra .............................................. 37
4.10 Determination of Coating Thickness from Phase Data ........... 38
5.0 Conclusion ............................................................ 40
6.0 Acknowledgements ...................................................... 40
7.0 References ............................................................ 41
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