What is Spectrometer Shot Noise?

Shot noise is a type of electronic noise that happens because electrons and photons are discrete particles. It arises in situations where the measurement involves counting events. In spectroscopy experiments, the event is a photon generating an electron. This process can be described by Poisson statistics, so the shot noise is approximately the square root of the number of events, √ N. Shot noise is also temperature and frequency independent. Two types of shot noise that show up in spectroscopy are photon noise and dark noise.