Transcript Spectroscopy - Jefferson Lab

Prologue
• Designer: Eric Kimsey
• The following powerpoint presentation was designed to
fulfill the requirements of the TAPS program at Jefferson
Labs in Newport News, VA summer 2006.
• This presentation was also designed to accompany and
expound upon the topic of Light and the Electromagnetic
Spectrum as required by the state of Virginia Physical
Science SOL’s (PS.9c).
Spectroscopy
A Tool of Astronomers
Definitions
• Spectroscopy- the study of the light from
an object.
• Spectrometer- an instrument which
spreads out light making a spectra.
• Spectra- range of electromagnetic energy
separated by wavelength.
Astronomers use spectroscopy
because it allows them to
determine the makeup of
stars… without having to be
present to take samples.
Studying an objects spectra can
tell scientists the composition of an
object, its temperature, its density
and its motion.
Two modern applications of
spectroscopy in space…
Mars Exploration Mission
The Mars Exploration Rovers were launched with the goal of
searching for and analyzing rock and soils on Mars. They utilized
several spectrometers to analyze samples.
Mini-TES: miniature thermal emission
spectrometer (examine rock, soil &
atmosphere)
MB: Mossbauer Spectrometer
(examine mineralogy of rocks &
soils)
APXS: Alpha Particle X-ray Spectrometer
(analyze elements in rocks & soils)
Cassini-Hyugen’s Mission
Mission: to gather information
on Titan (Saturn’s moon).
VIMS: Visual and Infrared
Mapping Spectrometer
(gather data about surface,
rings & atmosphere of Titan
and Saturn).
CIRS: Composite Infrared
Spectrometer (searches for
heat and by that gather
information on the object’s
composition.
2 Basic Types of Spectra
• Continuous- energy of all wavelengths
• Discrete- energy at a particular
wavelength
– Emission or bright lines
– Absorption or dark lines
Continuous Spectrum
• Also called thermal
or blackbody
spectra
• Spectra of stars,
planets, moons
• Depends on
temperature
Ex: sunlight passing
through a prism
Continuous Spectrum continued
Hotter objects
Shift toward this end
Longer
wavelength
Shorter
wavelength
Cooler objects
Shift toward this end
Discrete Spectrum
Absorption
Each element
has a unique
signature of
absorption
lines. That
pattern helps
scientists
identify the
element(s).
Ex: stars,
planets w/
atmospheres,
& galaxies
Spectra
Hot object
Cool,
thin gas
Absorption
spectrum
Discreet spectrum-
Emission
Again, the
pattern of the
lines
determines
the identity of
the element.
Ex: comets, nebula
& certain stars
Cold,
empty
space
Thin,hot
gas
Emission
spectrum
Spectra
Motion of Objects in Space
Compare the dark lines in the middle spectra to
the dark lines in the other two spectra.
Blue shift shows object is
moving toward the observer.
This shows the
normal position or
no motion.
This shows a red shift
meaning that the
object is moving away
from the observer.
Spectroscopy Lab
Determining the Spectra
of Certain Elements
What type of spectra
is shown here?
• Continuous
• Absorption
• Emission
What type of spectra
is shown here?
• Continuous
• Absorption
• Emission
Why does this picture represent
just the continuous spectrum of
light?
Light is just one portion of the
electromagnetic spectrum.
Name 5 other parts of the EM
spectrum.
Acknowledgements
•
•
•
•
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www.ipac.caltech.edu/Outreach/Edu/Spectra/spec.html
www.astronomynotes.com/lights4.htm
http://saturn.jpl.nasa.gov/spacecraft/instruments-cassini-cirs.cfm
http://pmo-sun.uoregon.edu/~astrosites.html
http://marsrovers.nasa.gov/overview
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