Transcript IR and Sample Prep Lecture

Infrared Waves
 What are they?
 Part of the electromagnetic spectrum
Electromagnetic Spectrum
 Wave in space with
electric and magnetic
properties
 Classified according to
the frequency of the
waves
 Frequency is the number
of waves that pass in a
certain amount of time
Electromagnetic Spectrum
 The higher the frequency the more
energy is in the waves
 When the frequency is very high the
waves can have ionizing energy
 Ionizing energy means it can change an
atom or molecule into an ion
 This can be extremely hazardous
Infrared Waves
 Do you ever use infrared waves?
Electromagnetic Spectrum
Electromagnetic Spectrum
Infrared Waves
 Infra means below
 Larger frequency than microwaves and
smaller than visible light
Uses for IR Waves






Remote controls
Medical – Skin therapy
Military – Target acquisition
Short range wireless communication
Astronomy - Photography
Spectroscopy
Spectroscopy
http://www.cem.msu.edu/~reusch/VirtualText/Spectrpy/InfraRed/infrared.htm#ir1
Spectroscopy
 What is it and how can we use it on
rocks?
 The study of the interaction between
radiation , light , and matter.
 http://www.nuance.northwestern.edu/Kec
kII/ftir1.asp
Fourier Transform Infrared
Spectroscopy
 What is it and how can we use it on
rocks?
Synchrotron Radiation Center
AM 0209 Line Map
Aperture = 20x20
Step = 45 µm
AM 0211 Area Map
Aperture = 20x20
Step = 30 µm
AM 0209 Spectra
French Curve
62.5
75.5
75.5
X 0.7
= 0.5795 % absorbance
0.7 Absorbance
Straight Line
67.75
75.5
X 0.7
= 0.6281 % absorbance
Determining the baseline can be
62.5
very subjective
Absorbance to Wt% Calculation
c = A / (Є b)
A = absorbance from spectra
Є= molar absorbtivity (L mol-1 cm-1) constant
b = path length of the sample (cm) sample thickness
c = concentration (mol L-1)
Beer-Lambert Law
http://teaching.shu.ac.uk/hwb/chemistry/tutorials/molspec/beers1.htm
Wt % to Pressure
Calculation
 VolatileCalc,
Newman and
Lowenstern, 2002
 Visual Basic for
Excel
 Pressure the
magma was under
when it crystallized
(bars)
Ice Thickness Calculation
• Pressure converted from bars to mH2O
• mH2O divided by density of ice
• Ice thickness