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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.
In the experiment, Ives and Stilwell used hydrogen discharge tubes as the source of canal rays which consisted primarily of positive H 2 + and H 3 + ions. (Free H + ions were present in too small an amount to be usable, since they quickly combined with H 2 molecules to form H 3 + ions.)
The ejected electrons are solvated by the water molecules on the sub-picosecond time scale. [ 23 ] [ 24 ] As the absorption spectrum of hydrated electrons, peaking 720 nm, is well known, [ 25 ] they can be characterized in a quantitative way.
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.
This cross section depends on the energy of the photon (proportional to its wavenumber) and the species being considered i.e. it depends on the structure of the molecular species. In the case of molecules, the photoionization cross-section can be estimated by examination of Franck-Condon factors between a ground-state molecule and the target ion.
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.
The electrons reach the P700 reaction center of photosystem I where they are energized again by light. They are passed down another electron transport chain and finally combine with the coenzyme NADP + and protons outside the thylakoids to form NADPH. Thus, the net oxidation reaction of water photolysis can be written as:
A white light source—emitting light of multiple wavelengths—is focused on a sample (the pairs of complementary colors are indicated by the yellow dotted lines). Upon striking the sample, photons that match the energy gap of the molecules present (green light in this example) are absorbed, exciting the molecules. Other photons are scattered ...