Forensic FTIR Instrumentation & Sample Preparation

Return to Forensic Training Home Page

Instructor: Dr. Brian C. Smith


Why Take This Course?

  • Learn to optimize scanning parameters for the best results
  • Discover the best troubleshooting techniques to keep your instrument healthy
  • Save time and money by choosing the right sampling technique the first time
  • Grasp how to properly analyze all your samples including solids, powders, liquids, and polymers
  • See how Attenuated Total Reflectance (ATR) makes analyzing many samples fast and easy


Course Length: Two 8-hour days taught online

            I. The Basics of FTIR

                        A. Introduction to Infrared Spectroscopy

                                    1. The Properties of Light

                                    2. What is an Infrared Spectrum?

                                    3. Infrared Spectroscopy: Good and Bad Points

                        B. The Advantage of FT-IR: Signal-to-Noise Ratio

                        C. The Disadvantage of FTIR: Water and CO2 Peaks


            II. How an FT-IR Works

                        A. Interferometers & Interferograms

                        B. How a Spectrum is Produced

                        C. Optimizing Spectral Quality

                        D. FTIR Hardware

                                    1. Infrared Sources

                                    2. Beamsplitters

                                    3. Detectors: DTGS and MCT

                                    4. The He-Ne Laser

                        E. Instrument Troubleshooting


            III. Dealing with Mixtures

                        A. Spectral Subtraction

                                    1. Theory

                                    2. Optimizing Subtraction Results

                                    3. Spotting Artifacts

                        B. Library Searching

                                    1. Background & Theory

                                    2. The Search Process

                                    3. Properly Interpreting Search Results

                                    4. Subtract & Search Again


            IV. Infrared Microscopes

                        A. How an Infrared Microscope Works

                        B. Preparing Samples

                        C. Applications

                                    1. Forensics

                                    2. Biological Samples

                                    3. Molecular Mapping


            V. Forensic Extractions and Reactions


            VI.Transmission Sampling

                        A. Advantages & Disadvantages

            VII. Transmission Sampling of Solids

                        A. KBr Pellets

                        B. Mulls


            VIII. Transmission Sampling of Polymers

                        A. Cast Films

                        B. The Heat & Pressure Method


            IX. Transmission Analysis of Fluids

                        A. Capillary Thin Films

                        B. Sealed Liquid Cells

                        C. Gases and Gas Cells


            X. Reflectance Sampling

                        A. Advantages

                        B. Disadvantages


            XI. Diffuse Reflectance (DRIFTS) for Solids and Powders

                        A. Sample Prep.

                        B. Applications

                        C. Abrasive Sampling


            XII. Attenuated Total Reflectance (ATR): A Technique for Many Samples

                        A. Theory & Background

                        B. Depth of Penetration

                        C. Depth Profiling

                        D. Quantitative Analysis


            XIII. Applications of ATR

                                    1. Polymers

                                    2. Semi-Solids: Gels, Waxes, Pastes etc.

                                    3. Organic & Aqueous Liquids

                                    4. Powders