Cargando…
Viscoelastic properties and efficient acoustic damping in confined polymer nano-layers at GHz frequencies
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 depend...
Autores principales: | , , , , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Nature Publishing Group
2016
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5025843/ https://www.ncbi.nlm.nih.gov/pubmed/27633351 http://dx.doi.org/10.1038/srep33471 |
_version_ | 1782454031976759296 |
---|---|
author | Hettich, Mike Jacob, Karl Ristow, Oliver Schubert, Martin Bruchhausen, Axel Gusev, Vitalyi Dekorsy, Thomas |
author_facet | Hettich, Mike Jacob, Karl Ristow, Oliver Schubert, Martin Bruchhausen, Axel Gusev, Vitalyi Dekorsy, Thomas |
author_sort | Hettich, Mike |
collection | PubMed |
description | 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. |
format | Online Article Text |
id | pubmed-5025843 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2016 |
publisher | Nature Publishing Group |
record_format | MEDLINE/PubMed |
spelling | pubmed-50258432016-09-22 Viscoelastic properties and efficient acoustic damping in confined polymer nano-layers at GHz frequencies Hettich, Mike Jacob, Karl Ristow, Oliver Schubert, Martin Bruchhausen, Axel Gusev, Vitalyi Dekorsy, Thomas Sci Rep Article 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. Nature Publishing Group 2016-09-16 /pmc/articles/PMC5025843/ /pubmed/27633351 http://dx.doi.org/10.1038/srep33471 Text en Copyright © 2016, The Author(s) http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
spellingShingle | Article Hettich, Mike Jacob, Karl Ristow, Oliver Schubert, Martin Bruchhausen, Axel Gusev, Vitalyi Dekorsy, Thomas Viscoelastic properties and efficient acoustic damping in confined polymer nano-layers at GHz frequencies |
title | Viscoelastic properties and efficient acoustic damping in confined polymer nano-layers at GHz frequencies |
title_full | Viscoelastic properties and efficient acoustic damping in confined polymer nano-layers at GHz frequencies |
title_fullStr | Viscoelastic properties and efficient acoustic damping in confined polymer nano-layers at GHz frequencies |
title_full_unstemmed | Viscoelastic properties and efficient acoustic damping in confined polymer nano-layers at GHz frequencies |
title_short | Viscoelastic properties and efficient acoustic damping in confined polymer nano-layers at GHz frequencies |
title_sort | viscoelastic properties and efficient acoustic damping in confined polymer nano-layers at ghz frequencies |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5025843/ https://www.ncbi.nlm.nih.gov/pubmed/27633351 http://dx.doi.org/10.1038/srep33471 |
work_keys_str_mv | AT hettichmike viscoelasticpropertiesandefficientacousticdampinginconfinedpolymernanolayersatghzfrequencies AT jacobkarl viscoelasticpropertiesandefficientacousticdampinginconfinedpolymernanolayersatghzfrequencies AT ristowoliver viscoelasticpropertiesandefficientacousticdampinginconfinedpolymernanolayersatghzfrequencies AT schubertmartin viscoelasticpropertiesandefficientacousticdampinginconfinedpolymernanolayersatghzfrequencies AT bruchhausenaxel viscoelasticpropertiesandefficientacousticdampinginconfinedpolymernanolayersatghzfrequencies AT gusevvitalyi viscoelasticpropertiesandefficientacousticdampinginconfinedpolymernanolayersatghzfrequencies AT dekorsythomas viscoelasticpropertiesandefficientacousticdampinginconfinedpolymernanolayersatghzfrequencies |