Observing with an alternative light source

• Our human eyes can only see light (a.k.a. radiation) in the visible spectrum.
• If we use special tools to look at different types of light (for example: a UV light), we might be able to make certain molecules or proteins fluoresce.
• When something fluoresces, it means that it absorbs UV light (in other words, it has an excitation wavelength of 390 nm) and reflects back light in a wavelength that the human eye can see (in other words, it has an emission wavelength between 400 nm and 780 nm), thus making it visible to us.
• Note 1: When using a UV light, pay attention to any colour that appears.
• Note 2: Some colours do not appear directly on the spectrum. They arise from different colour combinations:
  • Cyan: Blue and green combined (about 500 nm)
  • Pink: Predominantly red, with a bit of purple (about 700 nm)
  • Brown: Green and red combined (about 600 nm)
• List of common molecules and proteins that fluoresce.