| Date | Text | |
|---|---|---|
31 Mar 1997
Friedrich Hund |
death Friedrich Hund Died 31 Mar 1997 at age 101 (born 4 Feb 1896). Friedrich (Hermann) Hund was a German physicist known for his work on the electronic structure of atoms and molecules. He introduced a method of using molecular orbitals to determine the electronic structure of molecules and chemical bond formation. His empirical Hund's Rules (1925) for atomic spectra determine the lowest energy level for two electrons having the same n and l quantum numbers in a many-electron atom. (1) The lowest energy state has the maximum multiplicity consistent with the Pauli exclusion principle. (2) The lowest energy state has the maximum total electron orbital angular momentum quantum number, consistent with rule (1). They are explained by the quantum theory of atoms by calculations involving the repulsion between two electrons. |
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31 Mar 1997
Lyman Spitzer Jr. |
death Lyman Spitzer Jr. Died 31 Mar 1997 at age 82 (born 26 Jun 1914). American astrophysicist who advanced knowledge of physical processes in interstellar space and pioneered efforts to harness nuclear fusion as a clean energy source. He made major contributions in stellar dynamics and plasma physics. He founded study of the interstellar medium (gas and dust between stars from which new stars are formed). Spitzer studied in detail interstellar dust grains and magnetic fields as well as the motions of star clusters and their evolution. He studied regions of star formation and was among the first to suggest that bright stars in spiral galaxies formed recently. Spitzer was the first person to propose the idea of placing a large telescope in space and was the driving force behind the development of the Hubble Space Telescope. |
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