Here is an overlay of the curves.

Hi! It looks like both of your spectra are clipping -- hitting 100% and flattening. You can learn a bit about how to avoid this here:

https://publiclab.org/wiki/spectral-workbench-usage#Overexposure

Also, subtraction is possible using the new Spectral Workbench 2 operations -- take a look!

https://publiclab.org/wiki/spectral-workbench-tools

Hi Warren, thanx again for your input. Next time we get some sun I will try to work with reflective surfaces to reduce overall light intensity to avoid the overexposure. I guess the clipping of a single colour (for instance blue) will also affect the sum curve, won't it? I wasn't aware of that problem before I read your comment. Will be interesting to see, whether paper reflection changes the spectrum (i.e. absorbing colours...) Oh and thanx also for pointing me at the substraction of waves. Seems interesting. You know, I'm not a scientist and am just beginning to work with the spectrometer, but there seems to be a whole new world waiting to get discovered...

No problem and good luck! Post again -- i'm sure others would love to see some ideas for reducing overall light level.

Tried the substraction and yes, it does show the dips! Cool!

hello! Very colorful spectra, you don't really have to be a scientist to see the beauty in those colors, amazing, isn't it? Your right , you have a whole world of discovery just waiting for you, good luck!

Dave H

Thank you Dave. By the way, I had a look at your works and was very impressed. (Not that I would have understood most of it...) But one question came into my mind when I saw your setup: if you send the light through polymethylmethacrylate (however this molecule looks like) cuvettes - don't they also absorb light in certain (carbone/hydrogen) wavelengths? And if you use glass cuvettes - don't they absorb certain (silicate/oxygen) wavelengths? And how about the dilutant (water, alcohol, whatever...)? Do you create a "zero-spectrum" WITHOUT the actual agent you want to resaerch - i.e. only with the cuvette and dilutant in the light path - and then sustract the spectrum from the one you get WITH the agent?

I am so glad that you asked that question! I use 2 types of cuvettes, 1) Quartz - they have neutral UV absorption, so it passes right on through without any artifacts or problems.

2) I also use semi-micro UV-transparent disposable Cuvettes, which are made of a plastic material that can be used with most polar solvents, very handy.

I have created my own "blanks" that I use to zero out the spectrometer, kind of a round about way of doing it, but it works, I usually subtract my reference, which usually is the solvent and then subtract the blank from that and it cleans up the signal pretty nicely.

Okay, my sunlight did not show much UV because I let it shine through a glass window. Next time I will try without the glass. (Waiting for the next sunny day...) Not sure if that standard PLab-kit-camera can even detect UV... But that leads me to the next question: you seem to use a UV-Laser in some of your experiments. Is it right that it only uses a single UV-wavelength? That seems to mean that you only can explore matter that absorbs exactly THAT wavelength (and emitts perhaps a different one)? Is that right? What about "the other waves"?

Hi, I think the glass in the camera lens and the sensor limitations may prevent much UV, even without a window.

When we use a laser, we're mostly trying to generate fluorescence from the sample. See https://PublicLab.org/wiki/oil-testing-kit

Hope that helps!

Okay, now I understand. Thanx.