Observation of inhibited electron-ion coupling in strongly heated graphite

• Published in: Scientific reports Vol. 2; no. 1; p. 889
• Main Authors: White, T. G., Vorberger, J., Brown, C. R. D., Crowley, B. J. B., Davis, P., Glenzer, S. H., Harris, J. W. O., Hochhaus, D. C., Le Pape, S., Ma, T., Murphy, C. D., Neumayer, P., Pattison, L. K., Richardson, S., Gericke, D. O., Gregori, G.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 27-11-2012; Nature Publishing Group
• Subjects: 639/301; 639/766; 639/766/119; 704/445/846; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CONDENSED-MATTER PHYSICS; Diffraction; Energy; Energy transfer; Equilibrium; Experiments; GIANT PLANETS; Graphite; Heat; Humanities and Social Sciences; Laboratories; Lasers; Low temperature; MATERIALS SCIENCE; Melting; multidisciplinary; PHYSICS; Protons; Science; Science & Technology - Other Topics; Simulation; Temperature; Temperature effects; X-ray diffraction; X-rays
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep00889

Creating non-equilibrium states of matter with highly unequal electron and lattice temperatures (
T
ele
≠
T
ion
) allows unsurpassed insight into the dynamic coupling between electrons and ions through time-resolved energy relaxation measurements. Recent studies on low-temperature laser-heated graphite suggest a complex energy exchange when compared to other materials. To avoid problems related to surface preparation, crystal quality and poor understanding of the energy deposition and transport mechanisms, we apply a different energy deposition mechanism, via laser-accelerated protons, to isochorically and non-radiatively heat macroscopic graphite samples up to temperatures close to the melting threshold. Using time-resolved x ray diffraction, we show clear evidence of a very small electron-ion energy transfer, yielding approximately three times longer relaxation times than previously reported. This is indicative of the existence of an energy transfer bottleneck in non-equilibrium warm dense matter.