Isotope shift

The isotope shift is a physical effect that manifests itself in the fact that the spectral lines in the atomic spectra of different isotopes of the same element are shifted relative to one another. The reasons for this are differences in the mass, volume or magnetic moment of the atomic nucleus , which lead to slight changes in the electron shells of the atoms and thus to the shift or splitting of spectral lines.

The differences in the nuclear masses lead to differences in the reduced electron mass . The theory of this purely kinematic effect, which is particularly noticeable in light elements, was developed by DS Hughes and Carl Eckart. Among other things, the hydrogen isotope deuterium ² H was discovered by Harold Clayton Urey in 1931 due to the isotope shift to hydrogen ¹ H.

The differences in core size cause differences in the electrical charge distribution of the cores. This effect plays an important role in heavy elements and was explained by Aage Bohr and Victor Weisskopf .

The isotope shift, like all other physical isotope effects, is small and can consequently only be detected on the basis of high-resolution spectroscopic studies.

use

The isotope shift is exploited in the uranium enrichment process using lasers.

Individual evidence

^ DS Hughes and C. Eckart: The Effect of the Motion of the Nucleus on the Spectra of Li I and Li II . In: Phys. Rev. . 36, 1930, p. 694. doi : 10.1103 / PhysRev.36.694 .
^ Karl von Meyenn (Ed.): Wolfgang Pauli. Scientific correspondence with Bohr, Einstein, Heisenberg, among others: 1930-1939 . Springer, 1985, ISBN 978-3-540-13609-5 , pp. 73 ( Google Books [accessed March 3, 2011]).

swell

H. Kopfermann, Kernmomente, Leipzig 1940; 2. rework. Frankfurt 1956 edition.

[1] DS Hughes and C. Eckart: The Effect of the Motion of the Nucleus on the Spectra of Li I and Li II . In: Phys. Rev. . 36, 1930, p. 694. doi : 10.1103 / PhysRev.36.694 .

[2] Karl von Meyenn (Ed.): Wolfgang Pauli. Scientific correspondence with Bohr, Einstein, Heisenberg, among others: 1930-1939 . Springer, 1985, ISBN 978-3-540-13609-5 , pp. 73 ( Google Books [accessed March 3, 2011]).