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Spectroscopy - PowerPoint

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					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

Cool, thin gas

Absorption spectrum

Hot object

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

• • • • •

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

No way! Were you sleeping?
Back to question #1

YES, we have a winner!
To next question….

Pat yourself on the back!
Next question

That is a definite NO!
Back to 2nd question


				
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