Hydrogen, atomic beam apparatus

Fig. 4. Hydrogen atomic beam apparatus and scheme for laser cooling and magnetic trapping of hydrogen atoms.

Even if such high power levels cannot be sustained, it should still be possible to observe two-photon excitation with the help of more sensitive detection methods. Towards this end, U. Boesl and E. Hildum in our laboratory have recently completed construction of a hydrogen atomic beam apparatus, which permits the detection of 2S atoms via photoionization. The resulting charged particles are observed with a time-of flight mass spectrometer. Despite transit time broadening and uncompensated relativistic second order Doppler shifts, we hope to achieve line widths on the order of 1 Mhz in this... 

In initial experiments at Garching we have combined the IS1 — 2S spectrometer with another atomic beam apparatus for the excitation of the 25 — 45/4.0 transition in atomic hydrogen similar to the experiments in Paris [17,18,19], aiming at an improved measurement of the hydrogen ground state Lamb shift L(15) [20]. 

Endothermic Reactions and the Determination of Bond Dissociation Energies for Organometallic Fragments. The reaction of atomic nickel ion with molecular hydrogen to yield NiH+is substantially endothermic. Reaction cross sections for this process, measured using the ion beam apparatus shown in Figure 1, are displayed in Figure 3 for reactions 1 and 2 with HD as the neutral. 

The Lyman-a beam has been used recently for spectroscopy of atomic hydrogen. The IS — 2P transition has been driven for the first time with continuous coherent radiation. Results and a detailed description of the atomic hydrogen beam apparatus will be described elsewhere [36]. 

Light emission in collisions of He with H2 was studied37 for a He-beam energy of llOOeV. The apparatus has been described in the foregoing section. Emission from excited states of the hydrogen atom was found to be much stronger than emission from excited He-states which could not be detected at all. No emission from excited states of the hydrogen molecule could be found.86,37... 

Hydrogen Atom Rydberg Tagging Time-of-Flight Crossed Molecular Beam Apparatus... 

Fig. 3.15. Schematic diagram of the Atomic Beam 22-Pole Trap Apparatus (AB-22PT). This instrument has been developed for exposing cold trapped ions to an effusive beam of H atoms. The velocity distribution of the hydrogen beam depends on the temperature of the accommodator and the transmission features of the two hexapole magnets. A short description of this setup has been given recently.A detailed documentation of this sophisticated instrument is in preparation. ...

Fig. 5.10. Apparatus, not to scale, of Jones et al. (1993) for positron impact ionization of atomic hydrogen. Squares with crosses, Helmholtz coil shaded rectangles, stainless steel shielding black rectangles in beam line, lead shielding.

The systematic diagram in Fig.l depicts the experimental apparatus used for sliding tests in an ultra-high vacuum condition. It basically consists of a Si wafer specimen through which a direct current was supplied to heat the Si wafer, an Ag evaporating source by electron beam bombardment, quartz-oscillation film-thickness monitor, W-filament to dissociate hydrogen gas to adsorb the atomized hydrogen, and a slider arm with a diamond spherical pin which moves-reciprocally. 

---