| 释义 |
Umklapp Physics.|ˈʊmklæp|
Also umklapp.
[tr. G. umklappprozess (R. Peierls 1919, in Ann. d. Physik III. 1073), f. umklappen to turn down or over.]
Used attrib. to designate interactions in a crystal lattice in which their total momentum is not conserved, and the momentum of the initial excitations is reversed. Abbrev. U- or u-process.
[1937Physical Rev. LII. 690/1 These authors neglect transitions due to the ‘Umklappprozesse’ of Peierls.] 1951Proc. R. Soc. A. CCVIII. 90 Further measurements made on a corundum crystal confirm the importance of the ‘Umklapp’ processes, postulated by Peierls, in causing thermal resistance. 1960J. M. Ziman Electrons & Phonons iii. 133 We shall refer to U-processes, and, where wave vector is conserved,..N-processes. 1974H. E. Hall Solid State Physics viii. 207 An Umklapp process can be thought of as one in which a phonon is Bragg reflected simultaneously with absorbing or emitting another phonon. 1975H. M. Rosenberg Solid State vi. 99 In a continuous medium u-processes cannot occur. 1976F. Cap tr. Busch & Schade's Lect. Solid State Physics 67 At low temperatures the umklapp processes are essential for the establishment of thermal equilibrium in the crystal. |