Public Lab Research note


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EEM 2D Spectrums Showing Evidence of Attenuation from Imperfections in Acetate Film Strips

by dhaffnersr |

This is part 2 from my previous research post on Microscopic View of Public Lab's Acetate film slits

I conducted two exact experiments using the 0.09mm acetate film slit from Plab store and a new 0.11mm Gillette razor blade slit I constructed (open-air slit.) The EEM plot program in Spekwin32 allows me to calculate the degree of polarization of a selected spectrum and display it as a 2D graphic, which is very useful because I can see just how bad or how well the spectrum is cleaned up. ie., I can see the effects of fingerprints on the cuvette and scratches and imperfections on the cuvette also.

It also allows me to zoom in closely to any point in the spectrum for a closer look, that's what I did here. I replaced the old slit with the new one and did the same absorption experiments I did on Aug 10th with Eosin Y and Ethanol, using my Solux 4700K lamp.

The first section of this note will be the steps I took for constructing the new slit using a disposable Gillette double blade razor.

step_1_gillette_razor_blade_slit.png

gillette_razor_blade_slit_width_calibration_step_2.png

gillette_razor_blade_slit_front_view_step_3.png

gillette_razor_blade_slit_back_view.png

This next set are the EEM graphics illustrating the evidence of attenuation of detail due to imperfections in the acetate film strips used as slits.

09mm_011mm_slit_comparisons_aug_20.png

I would have attempted to construct another 0.09mm slit, but I could not find an appropriate piece of material the same thickness, so I used the thickness of the film strip itself as my calibration standard for the new slit and actually am happy I did, I got better detailed results with NO attenuation effects.



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1 Comments

I wanted to add this also to my note above,

Notice panel# 3, this is the 0.09mm acetate film slit with the embedded imperfections and how that attenuates the peak at 539nm, on panel# 4 this is not the case because of the new "open-air" design of the 0.11mm Gillette razor blade slit. Now what I did to prove my theory correct was, I took my plastic cuvette and put only a few minor scratches and finger prints on the forward facing side, and as you can see on panel# 5, the same attenuation that is seen on panel# 3 is apparent on panel# 5.

So perhaps it does make enough of a difference using the acetate film strips as entrance slits. In general, it may not matter too much but for detail chemical analysis it would make a difference because of resolution and skewing of data, because the detector doesn't discriminate between smudges or scratches, it records it as absorption...very bad!


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