| 释义 |
Lamb, n.2 Physics. (Lamb shift: formerly a main entry.)|læm|
[The name of Willis E. Lamb (b. 1913), U.S. physicist.]
Used attrib. to designate phenomena described, predicted, or demonstrated by Lamb, as Lamb dip, a drop in the output from a laser spectrometer at a particular frequency, as a result of atoms simultaneously absorbing two photons travelling in opposite directions; Lamb shift Physics [demonstrated by Lamb and R. C. Retherford in 1947], a displacement of energy levels in hydrogen and hydrogen-like atoms such that those with the same values of the quantum numbers n and j but different values of l are not coincident, as predicted by Dirac's theory, but separated by a very small amount (the level with the lower value of l being the higher).
1948Physical Rev. LXXIV. 1157 The effects treated are the Lamb shift, the correction of the g-factor..and the correction of the Compton scattering cross section. 1950Ibid. LXXVII. 745 (heading) Departure of the Lamb shift from the n-3 law in He+. 1958Condon & Odishaw Handbk. Physics vii. iv. 63/1 The Lamb shift has been interpreted..as resulting from changes in the electron self-energy which results from its interactions with the electromagnetic and electron-positron fields. 1964E. A. Power Introd. Quantum Electrodynamics i. 7 The modern versions of quantum electrodynamics have enabled a very accurate comparison to be made between theory and experiment. Well-known examples are the Lamb shift energy splitting of the 2S½ and 2P½ levels in hydrogen and the radiative corrections to the magnetic moment of the electron. 1965IEEE Jrnl. Quantum Electronics I. 351/1 When the amplitude of the second harmonic is zero, the Lamb dip just vanishes, and the second derivative of the turning curve at line center is zero. 1967Appl. Physics Lett. X. 304/1 A drop in saturated absorption, analogous to the Lamb dip, occurs when light is absorbed by atoms of the zero velocity class in the Doppler distribution of the low pressure neon. 1973McGraw-Hill Yearbk. Sci. & Technol. 111/1 Experimental programs to measure heavy-ion Lamb shifts are now in progress. 1974Physics Bull. Mar. 91/1 Lasers with frequencies locked to features such as the Lamb dip are routinely used in interferometry. 1989H. M. Georgi in P. Davies New Physics xvi. 449/2 Theorists used renormalisation to do finite calculations of quantum corrections to the first order results (such as..the Lamb shift). |