Chapter 11 Trace Elements: Metals, Paints and Soil

Slides:



Advertisements
Similar presentations
Trace Evidence ll: Metals, Paint, and Soil
Advertisements

Paint ToolMarks Tool Marks. Tool Marks A scratch or other microscopic marking left by the action of a tool on an object Evidentiary value: no two tool.
Forensic Characteristics of Soil. Soil: The Forensic Definition Any disintegrated surface material, natural and/or artificial, that lies on or near the.
Trace Evidence: Paint Criminalistics.
11-1 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein Chapter 11.
Unlocking Light The key to understanding the Cosmos.
The Nebular Theory, Matter, and Light 1. 1.Terrestrial, Jovian, and dwarf planets 2. 2.Nebular theory 3. 3.Matter – atoms and molecules 4. 4.Kinetic and.
11-1 PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ FORENSIC SCIENCE An Introduction By Richard Saferstein Trace Evidence ll:
Forensics Hair, Paint, and Fibers
8.4 Notes Examination of Paint.
Wednesday March 4, 2015 SWBAT discuss how glass is used in criminal in order to prepare for paint. Drill: Explain how we use density to solve measuring.
DIFFERENTIATE BETWEEN FISSION AND FUSION.
Radioactivity php.
Metal and Paint Analysis
Chapter 6: Inorganic Analysis
Honors Forensic Science.  Introduction  Organic substances constitute a substantial portion of physical evidence submitted to crime labs  Carbon does.
6- PRENTICE HALL ©2007 Pearson Education, Inc. Upper Saddle River, NJ CRIMINALISTICS An Introduction to Forensic Science, 9/E By Richard Saferstein.
+ Soil. + Soil Questions (1) What is soil? (2) What are the physical characteristics of soil? (3) What is the chemical composition of soil? (4) How do.
Question of the DAY Apr 1 In which of the following ways can trace amounts of poison in the human body be identified. A. Analysis of Hair B. Analysis of.
Forensic Paint Analysis
  Any disintegrated surface material, natural or artificial that lies on or near the Earth’s surface.  Natural= rocks, minerals, vegetation, animal.
Unit 2C Glass & Soil Evidence. Forensic Analysis of Glass Glass that is broken and shattered into fragments during the commission of a crime can be used.
Isotopic Abundance Reminder: bring a calculator to class.
Radioactivity SPS3. Students will distinguish the characteristics and components of radioactivity. Differentiate among alpha and beta particles and gamma.
Warm Up: If this car were in a hit and run accident and left the scene, what sort of evidence might you analyze from it?
Nuclear Chemistry , Nuclear Chemistry The study of the properties and reactions of atomic nuclei Atoms with identical atomic numbers.
Radioactivity and radioisotopes The nature of radiation Distinguishing Radiation Background Radiation.
Radioactive Decay Alpha, Beta, and Gamma Decay. Radioactivity Emission of particles and energy from the nucleus of certain atoms This happens through.
Pg  Explain the concept of an isotope  Understand how elements can be made radioactive.
Nuclear Chemistry The Atom The atom consists of two parts: 1. The nucleus which contains: 2. Orbiting electrons. protons neutrons Multiple nuclei is.
Methods of Chemical Analysis. Selecting an Analytical Technique  Organic vs. Inorganic materials  Organic:  Inorganic:  Quantitative vs. Qualitative.
Chemical Make-up of Fiber FT-IR: –Fourier-Transform Infrared Spectro. –Absorption of Infrared light by the polymer that comprise fiber result in characteristic.
Hair, Paint, and Fiber Evidence. A. Morphology of hair –1. HAIR IS AN APPENDAGE OF THE SKIN THAT GROWS OUT OF AN ORGAN KNOWN AS A HAIR FOLLICLE.
Nuclear Chemistry. The Atom The atom consists of two parts: 1. The nucleus which contains: 2. Orbiting electrons. protons neutrons.
Trace Evidence ii: Metals, paint & soil
Discrete Energy and Radioactivity Unit 7.1. Disclaimer: “We return to this for HL students in Topic 12, but for now it is maybe better to accept that.
Paint Trace Evidence K. Culbertson. Paint Physical evidence One of the most prevalent types of evidence to be analyzed Hit-and-run cases – Color, make,
MODELS OF THE ATOM A HISTORICAL PERSPECTIVE  Anything that has mass and takes up space  If you did not know this definition, how would you describe.
Nuclear Chemistry. The Atom The atom consists of two parts: 1. The nucleus which contains: 2. Orbiting electrons. protons neutrons.
Trace Evidence Paint. Introduction Manufactured products and even most natural materials contain small quantities of elements, or trace elements, in total.
Nuclear Chemistry. Radioactivity The process by which materials give off such rays radioactivity; the rays and particles emitted by a radioactive source.
Chapter 6 Inorganic Analysis 6.1 Notes Pg
Integrated Science Mr. Danckers Chapter 10.
Chapter 6: Inorganic Analysis. Inorganic Evidence Inorganic compounds do not contain carbon. Carbon Dioxide is an exception Carbon Dioxide is an exception.
Chapter 14: Trace Evidence II: Paint, Glass, & Soil.
NUCLEAR CHEMISTRY Chapter 20. Nuclear Chemistry Radioactivity is the emission of subatomic particles or high- energy electromagnetic radiation by the.
Chapter 3 Physical Properties: Forensic Characterization of Soil.
Forensics Hair, Paint, and Fibers. A. Morphology of hair –1. HAIR IS AN APPENDAGE OF THE SKIN THAT GROWS OUT OF AN ORGAN KNOWN AS A HAIR FOLLICLE.
Inorganic Analysis. Inorganic versus Organic ¾ of the weight of the earth’s crust is composed of SILICON and OXYGEN. What are some inorganic materials.
Paint Analysis.
Forensic Examination of Paint
Trace evidence ii: metals, paint, and soil
Types of Fractures by Projectiles
Forensic Science Ms. MacCormack Spring 2017
Paint One of the most common types of paint examined in the crime laboratory involves finishes emanating from automobiles. Paint spread onto a surface.
Chapter 6 INORGANIC ANALYSIS
Using Soil to Solve Crimes
Paint Ch11 Trace Evidence.
Unit 2C Glass & Soil Evidence
Forensic Definition of Soil
Characteristics of Soil Pg
Inorganic Analysis 6.1 Notes Pg
Forensic Soil Analysis
Forensic Characteristics of Soil
Examination of Paint Examine two paint samples to determine same origin Generally used in burglaries, hit-and-run accidents or vehicle accidents.
Glass & Soil Evidence.
Trace Evidence ll: Metals, Paint, and Soil
Forensic Paint Analysis
Chapter 11 Trace Evidence II
Presentation transcript:

Chapter 11 Trace Elements: Metals, Paints and Soil Objectives: Describe the usefulness of trace elements for the forensic comparison of various types of physical evidence. Distinguish between a continuous and line emission spectrum. Describe the parts of a simple emission spectrograph. Define protons, neutrons, and electrons, including their mass and charge relationships. Define atomic number and atomic mass number. Describe the orbital energy levels that are occupied by electrons. State what happens when an atom absorbs a definite amount of energy. Explain the phenomenon of an atom releasing energy in the form of light. Define an isotope. Define radioactivity. Explain how elements can be made radioactive.

Chapter 11 Trace Elements: Metals, Paints and Soil Objectives: Describe the components of paint. Classify automobile paints. List those examinations most useful for performing a forensic comparison of paint. Describe the proper collection and preservation of paint evidence. List the important forensic properties of soil. Describe the density-gradient tube technique. Describe the proper collection of soil evidence.

Forensic Analysis of Metals Trace Elements small quantities of elements found as impurities in all natural and manufactured products useful as “invisible”markers Kennedy Assassination bullets and fragments tested for silver and antimony match fragments in car Connally bullets indistinguishable Q1 and Q1 same Ag Sb ppm Kennedy bullets indistinguishable Q2 and Q14 Connally and Kennedy bullets are different

Atomic Structure Atoms composed of particles: Proton positive charge mass of 1 Neutron no charge Electron negative charge mass of 1/1837 Proton number distinguishes elements Atomic Number = # of protons Mass Number = sum of protons & neutrons  nucleus

Elements and Isotopes Isotope Radioisotope Atoms of same element same atomic number (electrons & protons) Have different atomic mass different number of neutrons Radioisotope unstable isotope decompose

Isotopes atoms of same element with different masses same # of protons different # of neutrons

Radioactivity high-energy particles released during decay Alpha rays largest/least energy He nucleus (2 protons & 2 neutrons) Beta Rays smaller/more energy electrons Gamma Rays smallest/most energy electromagnetic radiation

Neutron Activation Analysis atoms in a nuclear reactor gain neutrons becoming unstable releasing gamma rays can be detected to identify trace element determine if samples have common origin

Composition of Paint pigments binder impart color and opacity organic compounds binder polymer and solvent polymer holds pigments solvent evaporates after application

Automotive Paints Electrocoat Primer Primer Surfacer Basecoat organic resins electroplated to resist erosion (black or gray) Primer Surfacer epoxy modified polyester or urethane smooth out and hide seams Basecoat acrylic polymer pigments mica chips aluminum flakes resist weather, UV, acid rain Clearcoat acrylic or polyurethane improve gloss

Microscopic Paint Examination side by side comparison layer structure match # and sequence of colors “chip” fit

Paint Binder Characterization Pyrolysis Gas Chromatography decompose paint sample w/heat pyrolyze expose to high temperatures (500-1000°C) sample breaks up into many gaseous parts run these gases through GC forms a pyrogram can distinguish polymers Infrared Spectrophotometry each “binder” will have a characteristic absorption spectra

Paint Pigment Characterization Inorganic Pigments identified by emission spectra, neutron activation analysis, x-ray spectroscopy detects 15 to 20 elements most are common to all paints (unimportant) a few are rarely found (important) Organic Pigments UV Absorption Spectra Carbon Arc Emission Spectrometry “fingerprint” from “excited” electrons absorb energy move from ground state to excited state release “light” energy when they return to ground state Inductively Coupled Emission Spectrometry (ICP) argon gas and radio frequency induced coil form “hot plasma” aerosol of sample forced through the plasma forming an emission spectra

Significance of Paint Evidence Canadian Study 260 vehicle chips in wreck yard color, layer, and IR spec study all but one pair were distinguishable PDQ (Paint Data Query) Canadian data base started 1975 automotive paints layers, primer color, binder

Collection of Paint Evidence primary goal keep chip intact druggist fold or vial clothing package “whole” hit and runs get standard sample from undamaged area scrape to bare metal ¼ inch2 sample sufficient

Forensic Examination of Soil Visual Comparison color and texture soils compared must be dried under identical lab conditions Microscopic Comparison low power plant, animal, artificial materials high power minerals and rocks (geologist) Density Tube Gradient tubes with liquids of various densities density distribution pattern of soils useful only in conjunction with other tests

Collection of Soil Evidence must establish variation at scene standards collected at various intervals within 100 yard radius only surface soil each in individual plastic vials suspect samples take whole object containing soil car soil “lump form” sampling soil laid down in layers unique layering may have mre value