My spectroscopy-fu is failing me here -- the curve you're seeing is just the output wavelengths of your LED and laser, with a broad peak, right?

What would you happen if you compared it to a blank run -- with no cuvette at all -- just air? If the glass or quartz are absorbing much compared to air, you'd see that difference.

We used quartz cuvettes in lab doing all kinds of spectroscopy -- i think the trick was just don't try to measure something in the range that quartz absorbs... which I can't remember, but I might have a reference somewhere...

As far as your accuracy -- for the laser, getting 404nm doesn't sound bad at all! I can't remember for UV/vis, but for IR spectroscopy, our professional equipment gave us + or - one in the last digit of measurement.

If you did this again, could you do three separate runs for each test? to get an idea of the repeatability, and an average value and associated uncertainty to use as a starting point for any future calculations?

EDIT: Would you expect the cuvette to actually change the peak wavelength, or the signal intensity? I might need a refresher on the inverse square law...

Hey pdhixenbaugh, I was running this test because I know that glass can absorb UV radiation and the quartz cuvettes are suppose to let UV light pass without any absorption so I was testing the theory out with a uv laser and LED, the repeatability tests are a good idea though.

As far as the inverse square law, I don't think there is a problem since the distance is so very small.

Plus these series of tests where done straight ahead and not at a 90deg angle which would be normal in fluorescence spectrometry.

Thanks for replying have a good one!

Dave H