Effects of UV Radiation on Glass, Quartz and Plastic using UV LED and UV Laser Pointer
June 16, 2016
I ran this series of experiments 3 months ago using the old Plab 2.5 spectrometer kit, I used a 405nm UV laser pointer and A Prolight 1W high PWR UV LED [410nm].
I ran the same experiment again, only this time with a lot more experience and far better equipment. I am using my custom built DH 4.2 spectrometer [ slit width- 0.18mm/bandwidth = 2nm.]
Cuvettes used are the same one’s from my 2 previous wiki posts on “which cuvettes are optically best suited for spectroscopy.” This time the cuvettes are empty, for a much “truer” refractive index read.
Figure 1 shows the effect of the 410nm UV LED on all 3 cuvettes, notice that the peak wavelengths are the same for all 3 @ 392nm, FWHM for the glass and quartz cuvette were 20, and 19 for the UV plastic cuvette.
So no noticeable difference in UV absorption in either the plastic or glass cuvette, this could be caused by the wider beam dispersion of the LED @ 30 degrees, the LED is powered by a regulated power supply at 3.7vdc 350mA for maximum wavelength.
Figure 2 on the other hand, shows a slightly different effect because of the lasers tighter and more coherent wavelength. All 3 cuvettes demonstrate separate wavelengths and UV absorption effects. The plastic cuvette is @ 403nm, the glass @ 398nm and the quartz cuvette @ 401nm.
The effect of UV absorption is seen more clearly with the UV laser than with the UV LED, one interesting note is, the plastic UV cuvette is made from a polycyclic olefin material, which is a fairly new type of multi-polymer which the company BrandTech uses to manufacture its UV plastic disposable cuvettes (the very one’s I use now.)
In my opinion, with these results, I am inclined to believe that the plastic cuvette has outperformed even the UV quartz cuvette, and the glass cuvette indeed does absorb a degree of UV radiation.
Below are Figure 1 and figure 2 plot graphs for a clearer view