1) General: Not allowed; prohibited.
Past participle of forbid, from O.E. forbeodan, from for- "against" + beodan "to command" (O.E. biddan"to beg, ask, demand;" cf. Ger. bitten "to ask"); cf. Du. verbieden, O.H.G. farbiotan, Ger. verbieten.
Bažkam in classical Persian dictionaries "a keeping back, a preventing," from Av. paitigam- "to prevent," from paiti- "opposite, against, back, in return" (O.Pers. paity "agaist, back, opposite to, toward, face to face, in front of;" Mod.Pers. variants pâd- (→ anti-); cf. Skt. práti "opposite, against, again, back, in return, toward;" Gk. proti, pros "face to face with, toward, in addition to, near;" PIE *proti) + gam- "to come; to go," jamaiti "goes;" O.Pers. gam- "to come; to go;" Mod./Mid.Pers. gâm "step, pace," âmadan "to come" (cf. Skt. gamati "goes;" Gk. bainein "to go, walk, step;" L. venire "to come;" Tocharian A käm- "to come;" O.H.G. queman "to come;" E. come; PIE root *gwem- "to go, come").
Fr.: bande interdite
In → solid state physics, a range of → energy levels which is not attained by any electrons in a → crystal. In the energy level diagram forbidden bands appear as gaps between → allowed bands.
forbidden emission line
xat-e gosili-ye bažkam
Fr.: raie d'émission interdite
A → forbidden line in → emission.
Fr.: raie interdite
A spectral line emitted by atoms undergoing energy transitions not normally allowed by the → selection rules of → quantum mechanics. Forbidden emission lines form in low-density interstellar gas and are collisionally excited. They are designated by enclosing in brackets, e.g. [O III] and [N II], O and N representing oxygen and nitrogen atoms respectively.
Fr.: transition interdite
A transition between two quantum mechanical → states that → violates the quantum mechanical → selection rules.
→ forbidden; → transition.
Hayashi forbidden zone
zonâr-e baſkam-e Hayashi
Fr.: zone interdite de Hayashi
The region to the right the → Hayashi track, representing objects that cannot be in → hydrostatic equilibrium. Energy transport in these objects would take place with a → superadiabatic temperature gradient.
→ Hayashi track; → forbidden; → zone.
Fr.: raie semi-interdite
A → spectral line for which the upper and lower → energy levels have different values of S, the total → spin angular momentum. These lines violate the quantum mechanical → selection rule under → LS coupling, ΔS = 0. For example, the Ca I λ6573 line results from transition between the upper → triplet state (3P1) with a total spin angular momentum S = 1 and the → ground state, a → singlet state (1S0, total spin angular momentum S = 0). A semi-forbidden line is marked by a right bracket following the atom name, i.e. Ca I], in the above-mentioned case. Same as → interconnection line and → intersystem line.
Fr.: transition semi-interdite
An → atomic transition whose probability is reduced by a factor of the order of 106 because of → selection rules. Same as → interconnection line.
→ semi-; → forbidden; → transition.