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Chapters 4 and 5 Microscopy and Spectroscopy

Chapters 4 and 5 Microscopy and Spectroscopy. FRSC 7104 Criminalistics I Professor Bensley. FRSC 7104 - Chapters 4 and 5 Objectives. After studying these chapters, the student should be able to: Understand the fundamental concepts of a magnification system

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Chapters 4 and 5 Microscopy and Spectroscopy

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  1. Chapters 4 and 5 Microscopy and Spectroscopy FRSC 7104 Criminalistics I Professor Bensley

  2. FRSC 7104 - Chapters 4 and 5 Objectives After studying these chapters, the student should be able to: • Understand the fundamental concepts of a magnification system • Know and describe the important components of a microscope • Understand the concept of refractive index and how this idea is important in microscopy • Differentiate between polarized light microscopy and fluorescence microscopy • Apply the theories of UV/Vis, IR, and Mass spectrometry methods to Forensic applications

  3. FRSC 7104 - Chapters 4 and 5 Outline • Introduction to Microscopy • Compound Microscope

  4. Microscopy Terms • Binocular • Chromatic aberration • Condenser • Condenser diaphragm • Empty magnification • Field diaphragm • Field of view • Focal length • Köhler illumination • Numerical aperture • Objective • Ocular • Resolution • Spherical aberration • Virtual image

  5. Empty Magnification

  6. Focal Length

  7. Numerical Aperture NA = n sin u (where n = RI of medium and u = ½ angle of aperture of objective)

  8. FRSC 7104 - Chapters 4 and 5 Outline • Comparison Microscope

  9. Firearms Comparison Scope

  10. FRSC 7104 - Chapters 4 and 5 Outline • Stereomicroscope

  11. FRSC 7104 - Chapters 4 and 5 Outline • Polarizing Light Microscope (PLM)

  12. FRSC 7104 - Chapters 4 and 5 Outline • Plane polarized light

  13. FRSC 7104 - Chapters 4 and 5 Outline

  14. Cotton Under Polarized Light

  15. FRSC 7104 - Chapters 4 and 5 Outline • Refractive Index

  16. FRSC 7104 - Chapters 4,5,6 Outline • Snell’s Law

  17. Polarized Light Microscopy Terms • Analyzer • Anisotropic • Birefringence • Isotropic • Mounting media or mountants • Polarization colors • Polarizer • Snell’s Law

  18. Isotropic vs. Anisotropic

  19. FRSC 7104 - Chapters 4 and 5 Outline • Birefringence

  20. FRSC 7104 - Chapters 4 and 5 Outline • Becke Line

  21. FRSC 7104 - Chapters 4 and 5 Outline • Scanning Electron Microscope (SEM) The upper-left quadrant of each photomicrograph shows a field of view with the particle of interest within the smaller square in that field. The upper-right quadrant shows a zoomed-in view of the feature (the area from within the square in the upper-left quadrant), and the lower half shows the elemental spectrum acquired with the electron beam centered on the small (barely visible) square in the zoomed-in view. (A) Example of crystal with Ca, S, and O, which dominated the samples. (B) Example of fine particle aggregate that was prominent in the samples. (C) Example of fiber found in the samples. (D) Example of metallic particle (Ti) within fine particle aggregate. Source: http://www.ehponline.org/members/2003/5930/5930.html

  22. FRSC 7104 - Chapters 4 and 5 Outline • Review of Light and Matter

  23. FRSC 7104 - Chapters 4 and 5 Outline • Spectroscopic Techniques • UV/Vis

  24. FRSC 7104 - Chapters 4 and 5 Outline • Microspectrophotometry Microspectrophotometry of Fiber - 365 nm excitation • Controlled Substance Analysis

  25. FRSC 7104 - Chapters 4 and 5 Outline • UV Fluorescence • Drug Analysis, Dye Analysis

  26. FRSC 7104 - Chapters 4 and 5 Outline • Infrared (FTIR, ATR) • (Nearly) pure Controlled Substances, Paint, Hydrocarbons, Plastics and Polymers

  27. FTIR Microspectrophotometry of Paint

  28. FRSC 7104 - Chapters 4 and 5 Outline • Raman Spectroscopy • Mass Spectrometry • Atomic Spectroscopy (AAS, AES)

  29. FRSC 7104 - Chapters 4and 5Outline Chapter Summaries: • Microscopy provides fast, low-cost, and definitive results to the trained scientist • Light striking a material can cause a number of effects • Forensic science is concerned with mainly ultraviolet/visible and infrared spectroscopy • Instrumentation consists of a source of light, sample holder, method of breaking light into individual wavelengths and a detector

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