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Terahertz absorption by cellulose: Application to ancient paper artifacts

journal contribution
posted on 2023-06-09, 06:45 authored by Marco Peccianti, R Fastampa, A Mosca Conte, O Pulci, C Violante, J Lojewska, M Clerici, R Morandotti, M Missori
Artifacts made of cellulose, such as ancient documents, pose a significant experimental challenge in the THz transmission spectra interpretation due to their small optical thickness. In this Letter we describe a method to recover the complex refractive index of cellulose fibers from the THz transmission data obtained on single freely standing paper sheets in the 0.2–3.5 THz range. By using our technique, we were able to eliminate Fabry-Perot effects and recover the absorption coefficient of the cellulose fibers. The obtained THz absorption spectra are explained in terms of absorption peaks of the cellulose crystalline phase superimposed to a background contribution due to a disordered hydrogen bonds network. The comparison between the experimental spectra with THz vibrational properties simulated by density functional theory calculations confirms this interpretation. In addition, evident changes in the THz absorption spectra are produced by natural and artificial aging on paper samples, whose final stage is characterized by a spectral profile with only two peaks at about 2.1 THz and 3.1 THz. These results could be used to provide a quantitative assessment of the state of preservation of cellulose artifacts.

Funding

Route to guided TeraHertz backscattering Inspection and Analysis : THEIA; G1308; EUROPEAN UNION; PCIG14-GA-2013-630833

History

Publication status

  • Published

File Version

  • Accepted version

Journal

Physical Review Applied

ISSN

2331-7019

Publisher

American Physical Society

Issue

6

Volume

7

Page range

064019

Department affiliated with

  • Physics and Astronomy Publications

Research groups affiliated with

  • Sussex Centre for Quantum Technologies Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2017-06-16

First Open Access (FOA) Date

2017-06-16

First Compliant Deposit (FCD) Date

2017-06-16

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