radiationlessadj.
/ˌreɪdɪˈeɪʃnləs/, /ˌreɪdɪˈeɪʃənləs/, U.S. /ˌreɪdiˈeɪʃənləs/ Physics and Chemistry.
Not involving the emission of electromagnetic radiation.
ΘΚΠ
the world > matter > physics > electromagnetic radiation > [adjective] > not involving emission of
radiationless1919
1919 Proc. National Acad. Sci. U.S.A. 5 590 For any real motion, where the velocity is less than that of light,..radiationless orbits, other than straight lines uniformly described, are impossible.
1931 Proc. Royal Soc. A. 132 668 It is uncertain whether these γ-rays are actually emitted or whether the β-ray lines from which their existence is inferred are due to a radiationless transition.
1988 F. A. Cotton & G. Wilkinson Adv. Inorg. Chem. (ed. 5) xviii. 690 The system rapidly makes a radiationless transition (i.e., by loss of energy to the crystal lattice in the form of vibrations).
1994 J. Mehra Beat of Different Drum xii. 236 Feynman considered the radiationless scattering of the electron in the external electromagnetic field.
Derivatives
ˌradiˈationlessly adv. without the emission of electromagnetic radiation.
ΚΠ
1961 Jrnl. Molecular Spectroscopy 16 182 Emission occurs only from the lowest excited state, the higher levels degrading radiationlessly.
1983 Physical Rev. Lett. 50 1520 Energy gained by a downward jump of one electron is radiationlessly transferred to another electron, allowing it to make an upward energy jump.
2000 Proc. National Acad. Sci. U.S.A. 97 2976/2 The reaction A* → I proceeds radiationlessly.
This entry has been updated (OED Third Edition, June 2008; most recently modified version published online March 2022).
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adj.1919