Instructions
Periodic Table
Click on any element in the periodic table to add its spectrum and highlight its symbol in yellow.
Clicking a second time on the element will remove its spectrum and de-highlight it. Click on the Reset button to
remove all highlighted elements.
Emission/Absorption
The default is to show the emission spectrum of the selected elements. Clicking on the Absorption radio button will
display the absorption spectrum of the selected elements. Clicking on the Emission radio button will return the
default behavior.
Doppler Shift
The slider in the middle of the applet controls the Doppler shift of the spectrum. Moving the slider to the left
shifts the spectrum as if the source elements were moving toward the observer, and moving the slider to the right
shifts the spectrum as if the source elements were moving away from the observer. Each division on the scale represents
the source moving at 1/10 of the speed of light.
Note: The applet currently uses the classic model where vobs = vsrc + (vsrc / c). While this model
is accurate at low values of vsrc, it is increasingly less accurate as you approach the speed of light.
The Unknown Target
In order to create an unknown target to explore, press the New Target button. This will allow you to create an unknown spectrum, at which
point you can use the elements and Doppler shift (as necessary) in order to create an identical spectrum, thereby determining the composition
of the unknown. Once you believe that you have determined the unknown, press the Check button to see if you're right! If you're stuck, and
need a little bit of a help to get you back on track, the Hint button will give you a little information about the unknown.
If the applet doesn't show up (i.e. you just have a big grey box, or nothing at all)
Being a Java applet, the Spectroscopy applet needs a Java Virtual Machine to run. If you don't have one, you'll need to download the
Java plug-in from http://www.java.com.
More about the science
This applet displays the spectral lines in the visible spectrum (4000-7000 Angstroms) for the known elements. While it has data outside that envelope (from 2000-14,000 Angstroms),
only the visible portion is currently displayed. Also, there is no data available for elements above atomic number 99.
Element Data
The element data was obtained from the Atomic Spectral Database of the National Institute of Standards and Technology (NIST).
Further reading
The Electromagnetic Spectrum
The Doppler Effect
The Doppler Shift
Programming
This applet was created by Teravation, and all rights are reserved. While it currently supports multiple
languages, there are currently no additional languages defined for the applet. Future enhancements include additional languages, relativistic Doppler
Effect, and expansion of the spectral window into the UV and IR ranges. For information regarding hosting the applet, source code, custom development, or to report bugs
or suggestions, please contact us.
