Publication

Medium-range structural properties of vitreous germania obtained through first-principles analysis of vibrational spectra

Alfredo Pasquarello, Paolo Umari
2005
Journal Articles

Abstract

We analyze the principal vibrational spectra of vitreous GeO2 and derive therefrom structural properties referring to length scales beyond the basic tetrahedral unit. We generate a model structure that yields a neutron structure factor in accord with experiment. The inelastic-neutron, the infrared, and the Raman spectra, calculated within a density-functional approach, also agree with respective experimental spectra. The accord for the Raman spectrum supports a Ge-O-Ge angle distribution centered at 135 degrees. The Raman feature X-2 is found to result from vibrations in three-membered rings, and therefore constitutes a distinctive characteristic of the medium-range structure.

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https://infoscience.epfl.ch/entities/publication/75154030-9613-4dc0-912f-3d2f02b91e16

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Alfredo Pasquarello, Paolo Umari
2005
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/75154030-9613-4dc0-912f-3d2f02b91e16

About this result

Related concepts (32)

Raman spectroscopy

Raman spectroscopy (ˈrɑːmən) (named after Indian physicist C. V. Raman) is a spectroscopic technique typically used to determine vibrational modes of molecules, although rotational and other low-frequency modes of systems may also be observed. Raman spectroscopy is commonly used in chemistry to provide a structural fingerprint by which molecules can be identified. Raman spectroscopy relies upon inelastic scattering of photons, known as Raman scattering.

Rotational–vibrational spectroscopy

Rotational–vibrational spectroscopy is a branch of molecular spectroscopy concerned with infrared and Raman spectra of molecules in the gas phase. Transitions involving changes in both vibrational and rotational states can be abbreviated as rovibrational (or ro-vibrational) transitions. When such transitions emit or absorb photons (electromagnetic radiation), the frequency is proportional to the difference in energy levels and can be detected by certain kinds of spectroscopy.

Neutron scattering

Neutron scattering, the irregular dispersal of free neutrons by matter, can refer to either the naturally occurring physical process itself or to the man-made experimental techniques that use the natural process for investigating materials. The natural/physical phenomenon is of elemental importance in nuclear engineering and the nuclear sciences. Regarding the experimental technique, understanding and manipulating neutron scattering is fundamental to the applications used in crystallography, physics, physical chemistry, biophysics, and materials research.

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Medium-range structural properties of vitreous germania obtained through first-principles analysis of vibrational spectra

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