Publication

Negative plasmon dispersion in the transition-metal dichalcogenide 2H-TaSe2

Helmuth Berger
2009
Journal Articles

Abstract

We report about an electron energy-loss study on the dispersion of the charge-carrier plasmon in the charge-density-wave system 2H-TaSe2 above and below the metal-insulator transition. In both cases we find a negative slope, which is in remarkable contrast to the traditional prediction for metals based on the random-phase approximation. Possible scenarios for this intriguing phenomenon are discussed.

Official source

https://infoscience.epfl.ch/entities/publication/f27d387e-64ce-4a5b-921f-4d852d791b91

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Helmuth Berger
2009
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/f27d387e-64ce-4a5b-921f-4d852d791b91

About this result

Related concepts (16)

Post-transition metal

The metallic elements in the periodic table located between the transition metals to their left and the chemically weak nonmetallic metalloids to their right have received many names in the literature, such as post-transition metals, poor metals, other metals, p-block metals and chemically weak metals. The most common name, post-transition metals, is generally used in this article. Physically, these metals are soft (or brittle), have poor mechanical strength, and usually have melting points lower than those of the transition metals.

Surface plasmon resonance

Surface plasmon resonance (SPR) is a phenomenon that occurs where electrons in a thin metal sheet become excited by light that is directed to the sheet with a particular angle of incidence, and then travel parallel to the sheet. Assuming a constant light source wavelength and that the metal sheet is thin, the angle of incidence that triggers SPR is related to the refractive index of the material and even a small change in the refractive index will cause SPR to not be observed.

Heavy metals

Heavy metals are generally defined as metals with relatively high densities, atomic weights, or atomic numbers. The criteria used, and whether metalloids are included, vary depending on the author and context. In metallurgy, for example, a heavy metal may be defined on the basis of density, whereas in physics the distinguishing criterion might be atomic number, while a chemist would likely be more concerned with chemical behaviour. More specific definitions have been published, none of which have been widely accepted.

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