Article

Low-frequency modes in the Raman spectrum of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>s</mml:mi><mml:mi>p</mml:mi><mml:mtext>−</mml:mtext><mml:mi>s</mml:mi><mml:msup><mml:mi>p</mml:mi><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:math>nanostructured carbon

Carlo S. CasariDipartimento di Chimica, Materiali e Ingegneria Chimica ‘G. Natta’ and NEMAS—Center for NanoEngineered Materials and Surfaces, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, ItalyAndrea Li BassiDipartimento di Chimica, Materiali e Ingegneria Chimica ‘G. Natta’ and NEMAS—Center for NanoEngineered Materials and Surfaces, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, ItalyAlessandro BasergaDipartimento di Chimica, Materiali e Ingegneria Chimica ‘G. Natta’ and NEMAS—Center for NanoEngineered Materials and Surfaces, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, ItalyL. RavagnanDipartimento di Fisica, CIMAINA—Interdisciplinary Centre for Nanostructured Materials and Interfaces, Università di Milano, Via Celoria 16, I-20133 Milano, ItalyP. PiseriDipartimento di Fisica, CIMAINA—Interdisciplinary Centre for Nanostructured Materials and Interfaces, Università di Milano, Via Celoria 16, I-20133 Milano, ItalyCristina LenardiIstituto di Fisiologia Genenerale e Chimica Biologica, CIMAINA—Interdisciplinary Centre for Nanostructured Materials and Interfaces, Università di Milano, Via Trentacoste 2, I-20134 Milano, ItalyMatteo TommasiniDipartimento di Chimica, Materiali e Ingegneria Chimica ‘G. Natta’ and NEMAS—Center for NanoEngineered Materials and Surfaces, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, ItalyAlberto MilaniDipartimento di Chimica, Materiali e Ingegneria Chimica ‘G. Natta’ and NEMAS—Center for NanoEngineered Materials and Surfaces, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, ItalyDaniele FazziDipartimento di Chimica, Materiali e Ingegneria Chimica ‘G. Natta’ and NEMAS—Center for NanoEngineered Materials and Surfaces, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, ItalyC. E. BottaniDipartimento di Chimica, Materiali e Ingegneria Chimica ‘G. Natta’ and NEMAS—Center for NanoEngineered Materials and Surfaces, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, ItalyP. MilaniDipartimento di Fisica, CIMAINA—Interdisciplinary Centre for Nanostructured Materials and Interfaces, Università di Milano, Via Celoria 16, I-20133 Milano, Italy

2008lv

ABI

Abstract

Amorphous carbon films with $sp\text{\ensuremath{-}}s{p}^{2}$ hybridization, produced by supersonic cluster beam deposition, shows the presence of both polyynic and cumulenic species [L. Ravagnan et al., Phys. Rev. Lett. 98, 216103 (2007)]. Here, we present an in situ Raman characterization of the low-frequency vibrational region $(400--800\text{ }{\text{cm}}^{\ensuremath{-}1})$ of $sp\text{\ensuremath{-}}s{p}^{2}$ films at different temperatures. We report the presence of two peaks at 450 and $720\text{ }{\text{cm}}^{\ensuremath{-}1}$. The lower frequency peak shows an evolution with the variation of the $sp$ content and it can be attributed, with the support of density functional theory simulations, to bending modes of $sp$ linear structures. The peak at $720\text{ }{\text{cm}}^{\ensuremath{-}1}$ does not vary with the $sp$ content and it can be attributed to a feature in the vibrational density of states activated by the disorder of the $s{p}^{2}$ phase.

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Identifiers

DOI: 10.1103/physrevb.77.195444

Citations and references

Cited by 20 references

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