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Viscoelastic properties and efficient acoustic damping in confined polymer nano-layers at GHz frequencies

Hettich, Mike and Jacob, Karl and Ristow, Oliver and Schubert, Martin and Bruchhausen, Axel and Gusev, Vitalyi and Dekorsy, Thomas (2016) Viscoelastic properties and efficient acoustic damping in confined polymer nano-layers at GHz frequencies. Scientific Reports, 6, pp. 33471-33479. Nature Publishing Group. DOI: 10.1038/srep33471 ISBN 2045-2322 ISSN 2045-2322

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Official URL: http://www.nature.com/articles/srep33471

Abstract

We investigate the viscoelastic properties of confined molecular nano-layers by time resolved optical pump-probe measurements. Access to the elastic properties is provided by the damping time of acoustic eigenmodes of thin metal films deposited on the molecular nano-layers which show a strong dependence on the molecular layer thickness and on the acoustic eigen-mode frequencies. An analytical model including the viscoelastic properties of the molecular layer allows us to obtain the longitudinal sound velocity as well as the acoustic absorption coefficient of the layer. Our experiments and theoretical analysis indicate for the first time that the molecular nano-layers are much more viscous than elastic in the investigated frequency range from 50 to 120 GHz and thus show pronounced acoustic absorption. The longitudinal acoustic wavenumber has nearly equal real and imaginary parts, both increasing proportional to the square root of the frequency. Thus, both acoustic velocity and acoustic absorption are proportional to the square root of frequency and the propagation of compressional/dilatational acoustic waves in the investigated nano-layers is of the diffusional type, similar to the propagation of shear waves in viscous liquids and thermal waves in solids.

Item URL in elib:https://elib.dlr.de/107653/
Document Type:Article
Title:Viscoelastic properties and efficient acoustic damping in confined polymer nano-layers at GHz frequencies
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Hettich, MikeDepartment of Physics and Center for Applied Photonics, University of Konstanz, GermanyUNSPECIFIED
Jacob, KarlDepartment of Physics and Center for Applied Photonics, University of Konstanz, GermanyUNSPECIFIED
Ristow, OliverDepartment of Physics and Center for Applied Photonics, University of Konstanz, GermanyUNSPECIFIED
Schubert, MartinDepartment of Physics and Center for Applied Photonics, University of Konstanz, GermanyUNSPECIFIED
Bruchhausen, AxelDepartment of Physics and Center for Applied Photonics, University of Konstanz, Germany, Instituto Balseiro & Centro Atomico Bariloche (CNEA), and CONICET, ArgentinaUNSPECIFIED
Gusev, VitalyiLUNAM Universités, CNRS, Université du Maine, LAUM UMR-CNRS 6613, Av.O. Messiaen, 72085 Le Mans, FranceUNSPECIFIED
Dekorsy, ThomasGerman Aerospace Center, Institute of Technical Physics, GermanyUNSPECIFIED
Date:16 September 2016
Journal or Publication Title:Scientific Reports
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:6
DOI :10.1038/srep33471
Page Range:pp. 33471-33479
Publisher:Nature Publishing Group
ISSN:2045-2322
ISBN:2045-2322
Status:Published
Keywords:Polymers, Structural properties, Sufaces, Interfaces and thin film
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Laser Research and Technology
Location: Stuttgart
Institutes and Institutions:Institute of Technical Physics
Deposited By: Heidenreich, Angela
Deposited On:16 Dec 2016 16:44
Last Modified:10 Dec 2018 10:29

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