A background spectrum is a spectrum taken of experimental conditions without the sample of interest present. This captures background sources of light, such as room lights. It is not the same as the dark spectrum, which is the spectrum with no light present. However, the dark spectrum is included in the background spectrum, such that the dark spectrum does not need to be collected if a background spectrum is collected. In the SpectraWiz software, taking a background spectrum is done by taking a dark spectrum while the background lights are still on. The software then automatically subtracts the background for you. This is illustrated below. Here is the spectrum of a white light source with ambient sources of light present:
Here is the spectrum of just the ambient lights. This is the spectrum to be used as a background:
This is the final spectrum after the background is subtracted:
