Quenching metastable state

In order to investigate the competition between magnetic interaction and spin transition in (bpym, S), quenching experiments have been performed at 0.63 GPa. Fig. 7 displays the magnetic behaviour of the quenched sample at increasing temperatures. It can be inferred from the thermal dependence of XmT that [HS-HS] entities can be frozen-in as a metastable state at low temperatures. Heating the sample above ca. 60 K leads to re-formation of... 

Several cases in which excited ions are deactivated on collision have already been discussed in previous sections and are included in Tables I and II. Collisional deactivation of electronically excited ions (i.e., quenching of metastable states) quite likely occurs in competition with many of the reactive channels shown in Table I, although it has been specifically studied or discussed for only a few systems. Collisional deactivation is at east partly responsible for attenuation of the ion beam when the attenuation technique (described earlier) is employed to determine the abundance of electronically excited ionic states. 

Scattering studies with metastable atoms are in many cases easier (and less expensive) than experiments with ground-state atoms, The discussion that follows is mainly concerned with helium, as most of the information is available for this atom. Figure 2 shows a skeletal setup of the experiment. A helium beam from a supersonic nozzle source is excited by electron impact to its two metastable states. The singlet state can be quenched by the 2g radiation from a helium-gas discharge lamp ... 

Scattering has been measured for Ne + Ne, Ar + Ar, and Dr + Kr by different groups at thermal energies, but no data and potentials have been published so far, as the analysis is quite involved. First, it is impossible to quench one of the two metastable states without an expensive laser, so that an investigator is generally forced to work with mixtures and second, six potentials contribute coherently for the dominant 3P2 species. The cross sections for fine-structure changing collisions are small78 80 and hence can... 

Fig. 10. (Upper) Partial level scheme of pHe+, summarizing the six transitions between normally metastable states observed by the new HAIR, method (bold arrows). Only the vacuum wavelengths for transitions observed until now are shown (in units of nm). (Lower) Dependence of the quenching cross section ag by H2 (full symbols) and D2 (open symbols) on the quantum numbers n and l. Arrows pointing downwards indicate laser induced transitions between a metastable and a short-lived state, while those pointing upwards represent HAIR, transitions between a long-lived lower state and a H2-induced short-lived upper state. From Ketzer et al. [31,32]...

This paper reports a precision measurement of the Lamb shift in the n=2 state of hydrogen using separated oscillatory fields in conjunction with a fast atomic beam. Atoms in the 2 S 2 metastable state are produced through charge capture by protons in a gas target. The atoms pass thrugh two separated oscillatory fields whose relative phase is switched between 0 and ir. A rf quenching field and a solar blind... 

Mercury may be easily excited to the 6 aP2 state by 2537-A radiation or by electron impact, and the excitation energy may be removed partly or totally in collisions with unexcited atoms or molecules. It is generally recognized that collisions with noble-gas atoms do not result in excitation transfer to the 6 3P0 metastable state or in quenching to the 6 S, ground state [90-92] and that such processes can be accomplished only in collisions with molecules... 

Glass obtained by quenching a molten liquid to room temperature is an amorphous metastable state. 

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