Pahneš, from pahn (→ broad, present tense stem of pahnidan "to broaden" + -idan infinitive suffix) + eš verbal-noun suffix.
pahneš -e Doppler
Fr.: élargissement Doppler
In atomic physics, the broadening of an emission or absorption line due to the Doppler effect. Random motions of molecules or atoms of the gas that is emitting or absorbing the radiant energy shift the apparent wavelength of each emitter, and the cumulative effect of indivisual shifts is to broaden the line.
Fr.: élargissement instrumental
The broadening of a point source caused by the response functions of the telescope and the instrument used.
Fr.: élargissement de raie
A widening of → spectral lines due to any of several factors, including the → Doppler broadening, → instrumental broadening, → microturbulence, → pressure broadening, → rotational broadening, the → Stark effect, and the → Zeeman effect.
natural line broadening
pahneš-e zâstâri-ye xatt
Fr.: élargissement naturel de raie
The broadening of any spectral line due to the fact that excited levels have mean lives, which, by virtue of the uncertainty principle, implies a spread in the energy values.
Fr.: élargissement par pression
A broadening of spectral lines caused mainly by the stellar atmospheric density and the surface gravity of the star. The line strength of a spectral line depends on the number of atoms in the star's atmosphere capable of absorbing the wavelength in question. For a given temperature, the more atoms there are, the stronger and broader the spectral line appears. Denser stars with higher surface gravity will exhibit greater pressure broadening of spectral lines.
Fr.: élargissement rotationnel
The spectral line broadening caused by stellar rotation. Light from two rims of the star will be Doppler shifted in opposite directions, resulting in a line broadening effect. The line broadening depends on the inclination of the star's pole to the line of sight. The derived value is a function of ve. sini, where ve is the rotational velocity at the equator and i is the inclination, which is not always known. The fractional width (Δλ/λ) is of the order of 10-3 for B stars.