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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 21: POSTER: Dynamics and Diffusion

CPP 21.10: Poster

Mittwoch, 28. März 2007, 16:00–18:30, Poster B

Is lithium hydride LiH or LiH0.5? This is just a question of time! — •Tyno Abdul-Redah — Inst. f. Chemie, TU Berlin, Str. d. 17. Juni 135, 10623 Berlin, Germany.

The interactions of the particles in a macroscopic system lead to quantum correlated states in which the particles become invisible. The survival time of these states in condensed matter is generally expected to be very short because of the fast and effective decoherence due to interaction with the remaining environment. However, it is indeed possible to measure their effects if the experimental technique is fast enough, e.g., using neutron Compton scattering (NCS) with scattering times of attoseconds. NCS experiments on various solid compounds like metal hydrogen systems have been done [1]. The effect manifests itself by a strong anomalous decrease of the scattering cross section density. E.g., the ionic hydride lithium hydride appears then as LiH0.5 rather than LiH in the subfemtosecond time scale of the experiment [2]. The anomaly varies among others with scattering time and with temperature depending on the chemical bond and the electronic environment of the hydrogen in the particular chemical compound. The effect suggests that that the protons do not scatter individually. New experimental results on solid LiH, LaHx, NbHx will be presented. The importance of this effect for chemistry and physics will be outlined.

[1] T. Abdul-Redah, C. A. Chatzidimitriou-Dreismann, E. B. Karlsson, Neutron News 15 (2004) 14.

[2] T. Abdul-Redah and C. A. Chatzidimitriou-Dreismann, Physica B 350 (2004) 1035.