Title: JS 111: Physical Evidence Continued and Basic Properties of Light
1JS 111 Physical Evidence Continuedand Basic
Properties of Light
- Pre-class activities
- Review- Quiz (and Physical Evidence below)
- Announcements- No Class next monday 6 Sept- Happy
Labor Day! - Assignments
- Measurements and errors
- II. Physical Evidence Learning Objectives
- Define Physical Evidence
- Review proper CSI methods and documentation
- Review collection methods
- Define class vs individual characteristics
- III. Basic Properties of Light Learning
Objectives - Define the properties of light
- Define wavelength and frequency of light
- Understand the basics of excitation and emission
spectra - Semen Detection Examples
- IV. Team Fluorescent Applications
2Assignments
Assignment Due Weds 09/08/10- Required reading
Other references on fluorescence and semen
detection Read Chapter 1 in the book.- Pages
1-19. Read the following 2 articles. Write a 3
page summary, 3 questions and 3 answers. Submit
by email to Lee by 09/08/10 1200 noon. Bring hard
copy to class weds 090810. Introduction to
fluorescence- http//www.invitrogen.com/site/us/e
n/home/References/Molecular-Probes-The-Handbook/In
troduction-to-Fluorescence-Techniques.html Tutor
ial on Fluorescence and Fluorescent
Instrumentation downloaded from
http//fmrc.pulmcc.washington.edu/DOCUMENTS/FMRC29
9.pdf on 083010
3CSI Exercise 1- Measurements and Documentation
- In your small teams using the rulers you have
been provided, measure to the nearest 0.1 mm the
object for your team. - Team leaders should collect all measurements on
one paper. Write down the range of measurements
(eg 10.3-10.7mm) and calculate the average
measurement. - In addition, take measurements to document the
location of the object. - Once completed be sure everyone signs the paper
and hand it in.
4CSI Measurement Questions
- Did you all agree on the measurements?
- If no, what are 3 reasons which may cause the
discrepancy? (what are variables in
measurements?... what might we encounter in the
use of fluor measurements?) - For one of the reasons, design an experiment to
test your hypothesis. - Is there enough documentation for you to
reconstruct the location of the object.
5Theory of Light-1See http//micro.magnet.fsu.edu/
primer/lightandcolor/index.html for additional
information and review
- White light is composed of a range of colors
- ROYGBIV
- Red glass absorbs all component colors except red
passing through or transmitted - Color is a visual indication of an objects
ability to absorbing some and reflect other
components of visible light
6Theory of Light -2
- Light described as continuous wave or stream of
discrete energy particles - Light as a wave in up and down motions has
wavelength (lambda-) in nanometers - The frequency is the number of crests per unit
time - Speed of light is 300 million m/s- symbol c
- Frequency and wavelength are inversely
proportional - Fc/lambda
7Theory of Light-3
- Visible light is only a small part of the entire
electromagnetic spectrum - Normal light is a collection of waves possessing
a range of wavelengths and are out of step with
each other - When pulsating in unison they are coherent or
laser Light amplification by the simulated
emission of radiation
8Theory of Light-4
- Absorption of Electromagnetic Radiation
- Any substance exhibit selective absorption of
electromagnetic radiation - Different materials have different absorptions
- The selective absorption of a substance is
measured by an instrument called a
spectrophotometer. - It produces an absorption spectrum depicting the
absorption of light as a function of wavelength
or frequency. Absorption of UV, visible and IR
are particularly applicable for identification of
organic substances- How much- Beers Law- Akc - A absorption cconcentration kproportionality
9Spectrophotometer
- Instrument used to measure and record the
absorption spectrum of a chemical substance - Components- 1. Radiation source
- 1- Radiation source (UV, vis, IR)
- 2. Monochromator or frequency selector
- 3. Sample holder
- 4. Detection to convert electromagnetic radiation
into an electric signal (digitizer) - 5. Recorder
10Spectrum
- Different materials may have distinctively
different absorption spectra - Each spectrum may have distributions that are
different from others or may share
characteristics similar to other compounds
11Fluorescence microscopy permits the detection of
cellular and molecular events using color
12http//www.spectral-imaging.com/inner/fs_technolog
y.html
13Semen Detection Application
14Semen Detection on Skin