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In partial Fulfillment to the requirements of Chem 127:
BarBa |biadomang | Cua | DELA cruz | de chavez|dulos
Manatad | monroy | Narciso | nepomuceno | Pilar| Tan
Submitted to:Dr. Voltaire organo
The Cellphone Spectrometer:
What It Is, How It’s Made & How It Works
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Spectrometry:More than the purview of expert engineers
“In order to get across the idea, 'I can do it, and Ican see it, and I can understand it,' they've go tobuild the instrument themselves.”
- Alexander Scheeline, 2009
Light
Source
Sample
Holder
Diffraction
Grating
Detector
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Meet Alexander Scheeline.
He wanted to seestudents using their
cellphones in class. Not for texting or surfing the
Web, but as ananalytical chemistry
instrument .
Truly, all you need are afew basic, inexpensive
components and acellphone to build a
spectrometer .
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The cellphone is the photodetector thateverybody has.
If you can get the picture from the
cellphone into thecomputer , it's only
software that keeps you from building a
cheapspectrophotometer.
And so, Scheeline wrote the
software.
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The Cellphone Photodetector:Converting light into numbers
1. Light reaches thecamera’s detector
surface. 2. Regions in thedetector are sensitiveto color.
(Red, Green, Blue)
3. More light, moreelectrons, more charge.
4. Analog-to-DigitalConverter: Generates anumber proportional to
amount of charge.
The resulting number corresponds toa bitmap (BMP) file.
This is too large, so a compressedversion, JPEG, is usually used.
The software that Scheeline wroteanalyzes JPEG files, and it’s availableonline…
… so yes, we did it.
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The Cellphone Spectrometer: A construct out of household materials
All you actually need is a shoebox, an old disc youdon’t use anymore, some pipes, a camera-equipped
cellphone… and of course, knowledge ins ectrometr .
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The Cellphone Spectrometer:1. You need a sample first!
Anything colored can be your sample.Our group chose to analyze a yellow-orange colored
drink, melon juice.
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The Cellphone Spectrometer:2. Lights off, please.
Turning off the light is imperative!It will minimize the amount of stray
light .
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The Cellphone Spectrometer:3. The sample’s position matters.
The sample is now ready for analysis!
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The Cellphone Spectrometer:4. Don’t forget to take a blank!
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The Cellphone Spectrometer:5. Take a shot now.
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The Cellphone Spectrometer:5. Here’s the interface of Scheeline’s software.
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The Cellphone Spectrometer:6. Load reference, load sample.
Sample Referenc
eUpload the pictures into the program.
Load the picture of your reference reading by going to'file > load reference (right) > (your directory
pathway)', then do the same to your sample spectrum'
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The Cellphone Spectrometer:7. There’s a red end; there’s a blue end.
Once the spectra areuploaded, simply click on one
side of the sample spectrum on your screen.
A box will appear, asking you
to specify if it is the red orblue end of the spectrum.
Choose the correct answerand repeat the procedure
at the other end of yoursample.
There should now be a greenline connecting the red andblue ends of your spectrum.
Run through the sameprocedure with your
reference spectrum.
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The Cellphone Spectrometer:8. The sample and its absorbance
Spend a bit of time exploring the 'Plot trace selection'portion.
‘ ’ ‘
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The Cellphone Spectrometer:9. The sample and its transmittance
Spend a bit of time exploring the 'Plot trace selection'portion.
‘ ’ ‘
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The Cellphone Spectrometer:10. The sample and its intensity
Spend a bit of time exploring the 'Plot trace selection'portion.
‘ ’ ‘
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Yes, you can make your own cellphonespectrometer, too!
Just visit the site below for more details!
http://www.asdlib.org/onlineArticles/elabware/Scheeline _Kelly_Spectrophotometer/index.html