Atomic hydrogen emission mechanism

While two-photon absorption spectroscopy has been widely applied for precision measurements of atomic structure, the polarization correlation of the simultaneous two-photon emission from the metastable Is state of atomic hydrogen has only been measured very recently. The emission of the coincident two photons can be described by a single state vector which determines the circular and linear two-photon polarization. Compared to the two-photon cascade experiments the polarization correlation of the simultaneous two-photon decay of metastable hydrogen is conceptually closer to the original proposals by Bell and Bohm for tests of the foundation of quantum mechanics. More than SO years have elapsed since the famous Einstein-Bohr debate on microphysical reality and quantum formalism. The present and future outcome of the hydrogen two-photon correlation experiment is considered to be a most crucial test with regard to the rivalry between quantum mechanics and local realistic theories. 

In the previous section, we pointed out that the interpretation of atomic line spectra posed a difficult problem for classical physics and that Bohr had some success in explaining the emission spectrum for the hydrogen atom. However, because his model was not correct, he was unable to explain all features of the hydrogen emission spectrum and could not explain the spectra of multielectron atoms at all. A decade or so after Bohr s work on hydrogen, two landmark ideas stimulated a new approach to quantum mechanics. Those ideas are considered in this section and the new quantum mechanics— wave mechanics—in the next. 

It has been mentioned above that the value 29 kcal mol" for the energy of the Hg-H bond is incompatible with Kobozev s assumption about the decisive role of the emission of hydrogen atoms in their removal. Let us consider in greater detail the relation between our results and the emission mechanism. 

Making use of these sensors it is possible to establish the mechanisms underlying emission of hydrogen atoms hrom the surface of amorphous antimony. It appears that the phenomenon is specific only for... 

Pair annihilation of a positron e+ and an electron e by y-ray emission was briefly explained in Section 1.3. There, the hydrogen-like system ePe, or positronium Ps, was described quantum mechanically as a QBS having a finite lifetime r because of an absorption potential —z Vabs- This potential also causes positron flux loss, or positron absorption, in collisions with atoms. 

In 1913 Bohr amalgamated classical and quantum mechanics in explaining the observation of not only the Balmer series but also the Lyman, Paschen, Brackett, Pfund, etc., series in the hydrogen atom emission spectrum, illustrated in Figure 1.1. Bohr assumed empirically that the electron can move only in specific circular orbits around the nucleus and that the angular momentum pe for an angle of rotation 9 is given by... 

In 1963, Fessenden and Schuler [1] found during irradiation of liquid methane (CFLt and CD4) at 98 K with 2.8 MeV electron that the low-field line for both hydrogen and deuterium atoms appeared inverted (emissive signals) and that the central deuterium atom line was very weak. Although the cause of such anomalous ESR spectra was not clear at that time, similar anomalous signals have been observed in many reactions and have been called " Chemically Induced Dynamic Electron Polarization (CIDEP). CIDEP should be due to non-equilibrium electron spin state population in radicals and could also be explained later by the radical pair mechanism as CIDNP. 

Clyne and Thrush studied the reaction in a flow system hydrogen was dissociated into atoms in an electric discharge and nitric oxide was added at various points downstream of the discharge. They followed the kinetics by measurement of the intensity of the red emission due to excited HNO. The intensity of emission is proportional to the hydrogen atom and nitric oxide concentrations I = /o[H][NO] where /q is independent of total pressure. Hence, at a constant pressure and temperature //[NO] measured the relative concentration of hydrogen atoms. From their results they postulated the following mechanism... 

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