Public Lab Research note


Importing spectra from NIST and WebMineral.com to Spectral Workbench

by warren | August 13, 2013 16:16 | 374 views | 4 comments | #8995 | 374 views | 4 comments | #8995 13 Aug 16:16

Read more: publiclab.org/n/8995


Note: this may now be possible more easily using the JSON/CSV upload feature of Spectral Workbench.

What I want to do

To help with the flare spectroscopy effort, I wanted to try importing some known emission spectra from an online database, and started with a combination of the images available at WebMineral.com (which are cited from a 1906 now-public-domain source) and the list of emission lines at NIST. I started with lead, which NIST displays as Pb I, which I believe is the basic form of lead (I think Pb II and II refer to ions?). NIST offers this chart of emission lines:

And WebMineral.com offers this image of the lines:

lead.jpg

Although it mentions that they are not very "decisive" which I take to mean strong or easily visible. In any case I'd like to re-try this with copper and arsenic, which are also available. But by calibrating the lead spectrum from NIST data, we'll have a calibration source to work from for all the other elements, since the images are displayed with the same range of wavelengths.

I did a rough alignment here:

Screen_Shot_2013-08-13_at_11.38.31_AM.png

and it looks pretty good. So now I'll use two of the most obvious ones, at roughly 500nm and 600nm, to calibrate, using a modification/improvement on Chris Fastie's calibration macro: https://spectralworkbench.org/macro/warren/linear_calibration

My attempt and results

I used the lines at 262px, wavelength 500.5416nm and 522px, wavelength 600.1862nm and the calibration ran well:

https://spectralworkbench.org/analyze/spectrum/10863

Screen_Shot_2013-08-13_at_11.57.22_AM.png

Questions and next steps

Now we should be able to use the above spectrum #10863 to calibrate all the spectra offered at WebMineral.com, which include lithium, strontium, calcium, sodium, barium, molybdenum, boron, phosphorus, zinc, tellurium, antimony, lead, copper chloride, selenium, indium, arsenic, potassium, rubidium, and caesium.

I attempted this with arsenic: https://spectralworkbench.org/analyze/spectrum/10864

Screen_Shot_2013-08-13_at_12.04.40_PM.png

And with sodium, I compared the NIST/WebMineral spectrum with several independently collected sodium spectra, one of which I collected from burning salt, and one of which was made by Chris Fastie of a sodium streetlight. I also included two very distinct ones by contributor iglinax:

https://spectralworkbench.org/sets/show/545

Screen_Shot_2013-08-13_at_12.09.19_PM.png


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4 Comments

Selenium is of interest to those of us watching for coal impacts...how do i enter the Selenium flame standard into spectral workbench?

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wait, i think you answered the question above. I think i need some time to digest this.

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If you upload the image of selenium and clone the calibration of one of my spectra: https://spectralworkbench.org/tag/nist you'll have selenium.

And with Sreyanth's matching algorithms coming online soon, that'll hopefully be useful!

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Scott posted a selenium spectrum here: https://spectralworkbench.org/analyze/spectrum/12054

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