Observe objects with an alternative light source

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.
The visible spectrum. These are the colours your eyes can see. Note that the visible spectrum is surrounded by other forms of radiation that our eyes cannot see.