[matthew692692]

First post on here, so apologies if it's in the wrong category!

I'm a bit confused as to what two peaks on a UV-Vis mean. I have a peak around 360-380 nm and another peak at 600-640 nm and I'm required to discuss what they represent in relation to the observations in colour. I know that the first peak corresponds to the wavelength of violet light and the second peak corresponds to the wavelength of red light. To translate this to what I actually observe in the visible spectrum, I know that the complementary colours are what I actually see but when I do this, it tells me that what I see should be yellow-green, not dark blue like I observed.  My question is how do I use the two peaks to relate to what I actually observe? Do I take the difference of the wavelengths?

[Corribus]

A UV-Vis spectrum is an absorption spectrum.  You can convert it to a transmission spectrum to display what color light is transmitted by the sample.

Do be aware that the actual color you see with your eyes can be more complicated than what an absorption (transmission) spectrum tells you that you should see.  For one thing, your eyes do not perceive all colors equally.  For another, what your eyes pick up is transmitted light, but also light that is reflected, scattered and emitted (fluroescence) by the sample itself, particularly from indirect light sources (e.g., UV lights in the room).  In some cases, polarization of light can also change the observed color of a sample.