Helium Atoms

Some articles on helium, helium atoms, atoms, atom:

Helium–neon Laser - Construction and Operation
... medium of the laser, as suggested by its name, is a mixture of helium and neon gases, in approximately a 101 ratio, contained at low pressure in a glass envelope ... The gas mixture is mostly helium, so that helium atoms can be excited ... The excited helium atoms collide with neon atoms, exciting some of them to the state that radiates 632.8 nm ...
History - Discovery of Nuclear Fission
... elaboration of new nuclear physics that described the components of atoms ... In 1911, New Zealander Ernest Rutherford proposed a model of the atom in which a very small, dense and positively charged nucleus of protons (the neutron had not yet been ... particle—two protons and two neutrons bound together into a particle identical to a helium nucleus.) At the time, all known radioactive processes resulted in the nucleus losing no more mass than that ...
Carbon Dioxide Laser - Amplification
... and/or xenon (Xe) (a few percent usually only used in a sealed tube.) Helium (He) (The remainder of the gas mixture) The specific proportions vary according to the ... to ground state takes place by collision with cold helium atoms ... The resulting hot helium atoms must be cooled in order to sustain the ability to produce a population inversion in the carbon dioxide molecules ...
Helium Atom Scattering - Basic Principles - Why Use Helium Atoms?
... There are several advantages to using helium atoms as compared with x-rays, neutrons, and electrons to probe a surface and study its structures and phonon dynamics ... As mentioned previously, the lightweight helium atoms at thermal energies do not penetrate into the bulk of the material being studied ... Since they are neutral, helium atoms are insensitive to surface charges ...

Famous quotes containing the word atoms:

    Do but consider this small dust, here running in the glass,
    By atoms moved.
    Could you believe that this the body was
    Of one that loved?
    And in his mistress’ flame playing like a fly,
    Turned to cinders by her eye?
    Yes, and in death as life unblest,
    To have’t expressed,
    Even ashes of lovers find no rest.
    Ben Jonson (1572–1637)