The single-particle spectrum is a distribution of a physical quantity such as
energy
Energy () is the physical quantity, quantitative physical property, property that is transferred to a physical body, body or to a physical system, recognizable in the performance of Work (thermodynamics), work and in the form of heat and l ...
or
momentum
In Newtonian mechanics, momentum (: momenta or momentums; more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. ...
.
In formal
Quantum field theory
In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines Field theory (physics), field theory and the principle of relativity with ideas behind quantum mechanics. QFT is used in particle physics to construct phy ...
, a single-particle spectrum is defined as: "the spectrum of the operators of ''H'',
P on the space B."
The study of particle spectra allows us to visualize the global picture of particle production. This is especially helpful for visualizing the structure of
nanoparticles
A nanoparticle or ultrafine particle is a particle of matter 1 to 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions. At ...
.
The existence of a "non-smooth" single-particle spectrum is a piece of evidence (proof) that the
Fermi level
The Fermi level of a solid-state body is the thermodynamic work required to add one electron to the body. It is a thermodynamic quantity usually denoted by ''μ'' or ''E''F
for brevity. The Fermi level does not include the work required to re ...
exists.
The
spectrum are particles that are in space: "the single particle spectrum overlaps ... and the excitations of the electron gas becomes a particle."
This process uses
Raman spectroscopy
Raman spectroscopy () (named after physicist C. V. Raman) is a Spectroscopy, spectroscopic technique typically used to determine vibrational modes of molecules, although rotational and other low-frequency modes of systems may also be observed. Ra ...
, developed by
Chandrasekhar Venkata Raman.
References
{{reflist
External links
Nucleon-nucleon Interaction And The Nuclear Many-body Problem, The: Selected Papers Of Gerald E Brown And T T S Kuo (2010), p. 324
Physical quantities