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An anode ray (also positive ray or canal ray) is a beam of positive ions that is created by certain types of gas-discharge tubes. They were first observed in Crookes tubes during experiments by the German scientist Eugen Goldstein, in 1886. [1] Later work on anode rays by Wilhelm Wien and J. J. Thomson led to the development of mass spectrometry.
Figure 1. Ives–Stilwell experiment (1938). "Canal rays" (a mixture of mostly H 2 + and H 3 + ions) were accelerated through perforated plates charged from 6,788 to 18,350 volts. The beam and its reflected image were simultaneously observed with the aid of a concave mirror offset 7° from the beam. [1] Figure 2.
Crookes X-ray tube from around 1910 Another Crookes x-ray tube. The device attached to the neck of the tube (right) is an "osmotic softener". When the voltage applied to a Crookes tube is high enough, around 5,000 volts or greater, [16] it can accelerate the electrons to a high enough velocity to create X-rays when they hit the anode or the glass wall of the tube.
Eugen Goldstein (/ ˈ ɔɪ ɡ ən / OY-gən, German: [ˈɔʏɡeːn ˈɡɔlt.ʃtaɪn, ˈɔʏɡn̩-]; 5 September 1850 – 25 December 1930) was a German physicist.He was an early investigator of discharge tubes, the discoverer of anode rays or canal rays, later identified as positive ions in the gas phase including the hydrogen ion.
In light optics, the refractive index changes abruptly at a surface between regions of constant index: the rays are controlled with the shape of the interface. In the electron-optics, the index varies throughout space and is controlled by electromagnetic fields created outside the electron trajectories.
where I(d) is the intensity after the primary electron beam has traveled through the solid to a distance d. The parameter λ(E), termed the inelastic mean free path (IMFP), is defined as the distance an electron beam can travel before its intensity decays to 1/e of its initial value.
Because these latter rays passed through the holes, or channels, in the cathode, Goldstein called them "kanalstrahlen", or canal rays. He determined that canal rays are composed of positive ions whose identity depends on the residual gas inside the tube. It was another of Helmholtz's students, Wilhelm Wien, who later conducted extensive studies ...
By recording the attenuation of light for various wavelengths, an absorption spectrum can be obtained. In physics, absorption of electromagnetic radiation is how matter (typically electrons bound in atoms) takes up a photon's energy—and so transforms electromagnetic energy into internal energy of the absorber (for example, thermal energy). [1]