Triggering dynamics of the high-pressure benzene amorphization

Year: 2007

Authors: Ciabini L., Santoro M., Gorelli F.A., Bini R., Schettino V., Raugei S.

Autors Affiliation: European Lab Non Linear Spect, LENS, I-50019 Florence, Italy; INFM, I-50019 Florence, Italy; Univ Florence, Dipartimento Chim, I-50019 Florence, Italy; Univ Roma La Sapienza, CRS SOFT INFM CNR, I-00185 Rome, Italy; Scuola Int Super Studi Avanzati, SISSA ISAS, I-34014 Trieste, Italy; INFM, DEMOCRITOS Modeling Ctr Res Atomist Simulat, I-34014 Trieste, Italy.

Abstract: Success in designing and tailoring solid-state reactions depends on the knowledge of the mechanisms regulating the reactivity at the microscopic level. In spite of several attempts to rationalize the reactivity of crystals(1-5), the question of the existence of a critical distance for a reaction to occur remains unsolved. In this framework, the role of lattice phonons, which continuously tune the relative distance and orientation of the molecules, is still not fully understood. Here, we show that at the onset of the transformation of crystalline benzene to an amorphous hydrogenated carbon the intermolecular C-C distance is always the same ( about 2.6 angstrom) once collective motions are taken into account, and it is independent of the pressure and temperature conditions. This conclusion is supported by first-principles molecular-dynamics simulations. This is a clear demonstration of the role of lattice phonons in driving the reactivity in the crystalline phase by fine-tuning of the nearest-neighbour distances. The knowledge of the critical C-C distance can be crucial in planning solid-state reactions at moderate pressure.

Journal/Review: NATURE MATERIALS

Volume: 6 (1)      Pages from: 39  to: 43

More Information: The European Union, under contract RII3-CT2003-506350, the Italian Ministero dell’Università e della Ricerca Scientifica e Tecnologica (MURST) and ‘Firenze Hydrolab’, through a grant by Ente Cassa di Risparmio di Firenze, supported this work. The authors gratefully acknowledge M. Mezouar and the staff of ID30 at ESRF for the X-ray diffraction measurements and the CINECA Supercomputing Centre (Bologna, Italy) for allocation of computer time. Correspondence and requests for materials should be addressed to R.B.
KeyWords: State Organic-chemistry; Solid-state; Infrared-spectroscopy; Phase; Compression; Reactivity; Lattice; Stress
DOI: 10.1038/nmat1803

Citations: 195
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