Spectral linewidth


Spectral linewidth

The spectral linewidth characterizes the width of a spectral line, such as in the electromagnetic emission spectrum of an atom, or the frequency spectrum of an acoustic or electronic system. For example, the emission of an atom usually has a very thin spectral linewidth, as only transitions between discrete energy levels are allowed, leading to emission of photons with a certain energy.

Several definitions are used to quantify the spectral linewidth, e.g. the full width at half maximum (FWHM).

While the spectral width of a resonator in electronics depends on the parameters of the components, and therefore can be easily adjusted over a wide range, linewidths are typically more difficult to adjust in physics. For example, even a resting atom which does not interact with its environment has a non-zero linewidth, called the natural linewidth (also called the decay width), which is a consequence of the Fourier transform limit (classical description) and the Heisenberg uncertainty principle (quantum mechanical description). According to the uncertainty principle the uncertainty in energy, ΔE, of a transition is inversely proportional to the lifetime, Δt of the excited state:

 \Delta E \Delta t \gtrapprox \frac{\hbar}{2}.

In practice lines are further broadened by effects such as Doppler broadening.

See also


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Spectral width — In telecommunications, spectral width is the wavelength interval over which the magnitude of all spectral components is equal to or greater than a specified fraction of the magnitude of the component having the maximum value. In optical… …   Wikipedia

  • Spectral line — Continuous spectrum Emission line …   Wikipedia

  • Oscillator linewidth — The concept of a linewidth is borrowed from laser spectroscopy. The linewidth of a laser is a measure of its phase noise. The spectrogram of a laser is produced by passing its light through a prism. The spectrogram of the output of a pure noise… …   Wikipedia

  • Atomic spectral line — In physics, atomic spectral lines are of two types: * An emission line is formed when an electron makes a transition from a particular discrete energy level of an atom, to a lower energy state, emitting a photon of a particular energy and… …   Wikipedia

  • McCumber relation — The McCumber relation (or McCumber theory) refers to the effective cross sections of absorption and emission of light in the physics of solid state lasers [1][2]. Contents 1 Definition 2 Gain …   Wikipedia

  • telecommunications media — Introduction       equipment and systems metal wire, terrestrial and satellite radio, and optical fibre employed in the transmission of electromagnetic signals. Transmission media and the problem of signal degradation       Every… …   Universalium

  • Homogeneous broadening — If an optical emitter (e.g. an atom) shows homogeneous broadening, its linewidth is its natural linewidth (see spectral linewidth). In contrast, an inhomogeneously broadened emitter has a broader linewidth than the natural. Broadening in laser… …   Wikipedia

  • Bandwidth (signal processing) — Bandwidth is the difference between the upper and lower cutoff frequencies of, for example, a filter, a communication channel, or a signal spectrum, and is typically measured in hertz. In case of a baseband channel or signal, the bandwidth is… …   Wikipedia

  • Magnetic resonance imaging — MRI redirects here. For other meanings of MRI or Mri, see MRI (disambiguation). Magnetic resonance imaging Intervention Sagittal MR image of the knee ICD 10 PCS B?3?ZZZ …   Wikipedia

  • Planar Doppler velocimetry — (PDV), also referred to as Doppler Global Velocimetry (DGV), determines flow velocity across a plane by measuring the Doppler shift in frequency of light scattered by particles contained in the flow. The Doppler shift, Δfd, is related to the… …   Wikipedia