Laporten.
/laˈpɔːt/ Physics.
Used attributively with reference to the rule propounded by Laporte in 1924 ( Zeitschr. f. Physik 23 135), that electron transitions occur only between atomic states whose l quantum numbers differ by ±1 or (alternatively) between states of opposite parity (a rule which holds for electric dipole transitions).
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Laporte1930
1930 Pauling & Goudsmit Struct. Line Spectra vi. 94 The empirical rule that transitions will occur only from a state for which the li sum..is odd to one for which it is even, or vice versa, is called the ‘Laporte rule’.
1945 J. W. T. Spinks tr. Herzberg Atomic Spectra (ed. 2) iv. 154 For the particular case of two electrons i and k, the Laporte rule may be formulated: when Δli = ±1, Δlk must be 0 or +2 or −2, and vice versa.
1966 McGraw-Hill Encycl. Sci. & Technol. (rev. ed.) IX. 566/1 The Laporte rule of atomic spectroscopy..depends on the fact that the electric dipole radiation field has odd parity.
1966 C. S. G. Phillips & R. J. P. Williams Inorg. Chem. II. xxi. 120 The most common type of transition giving rise to lanthanide spectra is that associated with a rearrangement of electrons inside the 4f sub-shell... Such transitions are Laporte forbidden (i.e. forbidden by first-order wave-mechanical treatment) so that the intensity of absorption is weak.
1977 I. M. Campbell Energy & Atmosphere viii. 220 The Laporte rule precludes transitions between states which are derived from the same electronic configuration.
1989 A. Salzer tr. Elschenbroich & Salzer Organometallics xiv. 243 Direct generation of an LF state (d–d transition) would be Laporte-forbidden.
This entry has not yet been fully updated (first published 1997; most recently modified version published online September 2018).
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