Molecular beam

Source: Wikipedia, the free encyclopedia.

A molecular beam is produced by allowing a

electrical fields and magnetic fields.[1] Molecules can be decelerated in a Stark decelerator or in a Zeeman slower
.

History

The first to study atomic beam experiments was Louis Dunoyer de Segonzac 1911, but were simple experiments to confirm that atoms travelled in straight lines when not acted on by external forces.[2]

In 1921, Hartmut Kallmann and Fritz Reiche wrote[3] about the deflection of beams of polar molecules in an inhomogeneous electric field, with an ultimate aim of measuring their dipole moments. Seeing the page proofs for the Kallman and Reiche work prompted

University of Frankfurt am Main
to rush publication of his work with Walther Gerlach on what later became known as the Stern–Gerlach experiment. (Stern's paper references the preprint, but the Kallman and Reiche work would go largely unnoticed.[4])

When the 1922 Stern-Gerlach paper appeared is caused a sensation: they claimed to have experimentally demonstrated "space quantization": clear evidence of quantum effects at a time when classical models were still considered viable.[4]: 50  The initial quantum explanation of the measurement -- as an observation of orbital angular momentum -- was not correct. Five years of intense work on quantum theory was needed before it was realized that the experiment was in fact the first demonstration quantum electron spin[2] Stern's group would go on to create pioneering experiments with atomic beams, and later with molecular beams. The advances of Stern and collaborators led to decisive discoveries including: the discovery of space quantization; de Broglie matter waves; anomalous magnetic moments of the proton and neutron; recoil of an atom of emission of a photon; and the limitation of scattering cross-sections for molecular collisions imposed by the uncertainty principle[2]

The first to report on the relationship between dipole moments and

KCl) was Erwin Wrede in 1927.[5][4]

In 1939

Herbert J. Zeiger and Charles H. Townes was made possible by a molecular beam of ammonia and a special electrostatic quadrupole focuser.[9]

The study of molecular beam led to the development of molecular-beam epitaxy in the 1960s.

See also

References

  1. PMID 22449067
    .
  2. ^
    S2CID 120812185
    .
  3. S2CID 119947742
    .
  4. ^
    ISBN 978-3-030-63962-4
  5. S2CID 120815653
    .
  6. ISSN 0034-6861
    .
  7. ISSN 0031-899X
    .
  8. ^ The Rabi molecular-beam method - The Feynman Lectures on Physics
  9. ISSN 0031-899X
    .
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