Single-particle spectrum

The single-particle spectrum is a distribution of a physical quantity such as energy or momentum.

In formal Quantum field theory, a single-particle spectrum is defined as: "the spectrum of the operators of H, P on the space B."^[1]

The study of particle spectra allows us to visualize the global picture of particle production.^[2] This is especially helpful for visualizing the structure of nanoparticles.^[3]

The existence of a "non-smooth" single-particle spectrum is a piece of evidence (proof) that the Fermi level exists.^[4]

The spectrum are particles that are in space: "the single particle spectrum overlaps ... and the excitations of the electron gas becomes a particle."^[5] This process uses Raman spectroscopy, developed by Chandrasekhar Venkata Raman.^[3]