Hyperfine structure atomic hydrogen

Theoretical analysis. Precise theoretical calcur lations of atomic hyperfine structures are possible only in hydrogenic systems, for example the 1 2 ground states... 

Figure Bl.4.9. Top rotation-tunnelling hyperfine structure in one of the flipping inodes of (020)3 near 3 THz. The small splittings seen in the Q-branch transitions are induced by the bound-free hydrogen atom tiiimelling by the water monomers. Bottom the low-frequency torsional mode structure of the water duner spectrum, includmg a detailed comparison of theoretical calculations of the dynamics with those observed experimentally [ ]. The symbols next to the arrows depict the parallel (A k= 0) versus perpendicular (A = 1) nature of the selection rules in the pseudorotation manifold.

The proton is the lightest nucleus, with atomic number one. Other singly charged nuclei are the deuteron and the triton, which are nearly two and three times as heavy as the proton, respectively, and are the nuclei of the hydrogen isotopes deuterium (stable) and tritium (radioactive). The difference in the nuclear masses of the isotopes accounts for a part of the hyperfine structure called the isotope shift. 

Later, after experiments performed by Rabi, Lamb and Kusch and their colleagues, it was discovered that the actual hydrogen spectrum was in part in contradiction to Dirac theory (see Fig. 1). In particular, the theory predicted a value of hyperfine structure interval in the ground state of the hydrogen atom, different from the actual one by one part in 103, and no splitting between 2si/2 and... 

Abstract. Muonium is a hydrogen-like system which in many respects may be viewed as an ideal atom. Due to the close confinement of the bound state of the two pointlike leptons it can serve as a test object for Quantum Electrodynamics. The nature of the muon as a heavy copy of the electron can be verified. Furthermore, searches for additional, yet unknown interactions between leptons can be carried out. Recently completed experimental projects cover the ground state hyperfine structure, the ls-2s energy interval, a search for spontaneous conversion of muonium into antimuonium and a test of CPT and Lorentz invariance. Precision experiments allow the extraction of accurate values for the electromagnetic fine structure constant, the muon magnetic moment and the muon mass. Most stringent limits on speculative models beyond the standard theory have been set. 

So far, we have considered each atomcule state as a single state with quantum numbers (n, l). More precisely speaking, however, since an electron in the Is orbital is coupled to the antiproton, each state has a hyperfine structure, as is well known for the hydrogen atom. In the present atomcule case, the situation is... 

Abstract. The usefulness of study of hyperfine splitting in the hydrogen atom is limited on a level of 10 ppm by our knowledge of the proton structure. One way to go beyond 10 ppm is to study a specific difference of the hyperfine structure intervals 8Au2 — Avi. Nuclear effects for axe not important this difference and it is of use to study higher-order QED corrections. 

The hyperfine splitting of the ground state of the hydrogen atom has been for a while one of the most precisely known physical quantities, however, its use for tests of QED theory is limited by a lack of our knowledge of the proton structure. The theoretical uncertainty due to that is on a level of 10 ppm. To go farther with theory we need to eliminate the influence of the nucleus. A few ways have been used (see e. g. [1]) ... 

N. Ramsey Atomic Hydrogen Hyperfine Structure Experiments . In Quantum Electrodynamics, ed. by T. Kinoshita (World Scientific, Singapore 1990) pp. 673-695... 

The hyperfine structure of the Is and 2s levels can be obtained precisely for the hydrogen atom and its isotops3 and for the helium-3 ion. 

A major step forward in our knowledge of interstellar matter was made in 1951 with the discovery of the first interstellar spectral line in the radio range, the famous X21 cm hyperfine structure line of atomic hydrogen. Most of our present knowledge of the distribution and physical state of interstellar matter in our Galaxy is based on observations of this line. At first it looked as... 

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