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Spectrometry activities



This page is still under active development and may be incomplete; please help to bring it to completion!

Now that you have a working spectrometer, what do you point it at? Give these experiments a shot. If you haven't yet, you should first calibrate your spectrometer with a CFL bulb.

Please add your own activity ideas, and mention how much time it'll take, an estimate of the cost, etc.

1. Measure gases in the atmosphere

Please note: this will only work with a device that can measure near-infrared light; one based on a modified webcam like the Desktop Spectrometry Kit.

This is a simple activity and a good starting place. Simply go outside during the day and point the spectrometer at an evenly illuminated part of the sky -- cloud or blue sky both work.

Even though air is pretty clear, pointing your spectrometer through miles of the atmosphere places many molecules between your spectrometer and your light source (AKA the sun). Because of the sheer amount of molecules, you can see lines where CO2, O2, O3, and water vapor have absorbed part of the spectrum. These are known as the Frauenhofer lines.

Look at other people's atmospheric spectra: for example, see: https://spectralworkbench.org/analyze/spectrum/913 (image below) and browse other examples here: https://spectralworkbench.org/tag/sunlight

Explore more and share: try pointing your spectrometer different directions in the sky, both towards and away from the sun. Where did you point your spectrometer to get the clearest absorption lines? Any idea why? Post a research note with your data and describe what you did.

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2. Point it at different types of light bulb

Now let's try measuring artificial light sources. Go indoors and find some different kinds of light bulbs like LEDs, incandescent bulbs, and fluorescent bulbs (try "warm" and "cool" ones!). Turn them on and point your spectrometer at them. Notice how much less of "the rainbow" you see compared to the sun - see the distinct emission lines of the mercury spectrum from mercury vapor in the lamps. You can read more about measuring emission spectra (especially in flames) here: http://publiclab.org/wiki/spectrometry-sampling#Flame+spectroscopy

Incandescent: (more examples)

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LED (more examples)

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Fluorescent: (more examples)

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Neon: (more examples)

See these examples of neon lights: http://publiclab.org/notes/cfastie/2-23-2013/neon

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Lasers: Try different colors of lasers - each of which will produce only a narrow band of colored light. Consider how to measure it without overloading the spectrometer with too much light. (more examples)

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Expand your toolkit

For these activities, you'll need a few more supplies beyond what comes in the kit, such as a green laser, sample containers, and other things. Also see the Spectrometry Sampling page for advice and tips on measuring liquid, solid, or gas samples.

[sodium flame](https://i.publiclab.org/system/images/photos/000/001/634/original/IMG_1794.JPG)

Detect sodium in table salt

15-20 minutes, 1 candle, bunsen burner or propane burner With a candle and a small spray bottle of salt water, you can measure the emission spectrum of the sodium in table salt.

Read more about this type of activity here

olive-oils

Detect chlorophyll in olive oil

15-20 minutes, 1 green laser or strong UV light

Shine a laser or a very strong UV light through a sample in a square-sided transparent container. Shine the light perpendicular to the direction the spectrometer is pointed, so that you measure only the color emitted by the sample, and not the green laser or UV light itself. If your olive oil has enough chlorophyll (especially greenish, extra-virgin olive oils), you'll be able to see a yellow, orange, or reddish glow. Since the laser (or UV light) is producing no red, orange, or yellow light, that light must have been produced by the "excited" chlorophyll.

The hardest part of this activity (still not a solved problem!) is getting enough light from the glowing sample to be detected by the camera. Please share your work if you're able to get it to work!

Read more about this type of activity here and about using lasers to do this here


Advanced tests

Help advance this project by attempting new tests which have not been fully explored yet -- please share your results if you manage to record data for one of these!

Measure other things in your kitchen

Try scanning a solution of alum? Mineral supplements dissolved in water? http://www.amazon.com/b/ref=dp_brw_link?node=3774271

Oils

Motor oil or olive oil - compare two types of oil. Garage version: try to test oil from your car. (expand this description)

Also take a look at the Spectrometry Sampling page to learn about oil sampling setups.

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Laundry detergents

Try to detect blueing dyes in laundy detergent UV light:

lycopene

Blending green and red tomatoes in alcohol for comparison, and to detect lycopene.

Comparing foods

Great documentation has been posted about using absorption spectroscopy (shining a full spectrum light like a halogen through a sample, often blended); please add to this list if you find more:

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A graph of different grades of maple syrup, by Chris Fastie

Beer's Law

Varying concentrations of liquids like coffee, wine, soda, juice. Try to demonstrate Beer's Law by diluting your sample with 50% water, repeatedly.

Venture off into the unknown.

See Spectral Analysis Techniques for an overview of different kinds of spectrometry.

Read about sample preparation of liquids and solids, and what kinds of sample containers to use: http://publiclab.org/wiki/spectrometry-sampling


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