Linear and helical cesium iodide atomic chains in ultranarrow single-walled carbon nanotubes: impact on optical properties

Reza J. Kashtiban*, Maria G. Burdanova, Andrij Vasylenko, Jamie Wynn, Paulo V.C. Medeiros, Quentin Ramasse, Andrew J. Morris, David Quigley, James Lloyd-Hughes, Jeremy Sloan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)
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One-dimensional (1D) atomic chains of CsI were previously reported in double-walled carbon nanotubes with ∼0.8 nm inner diameter. Here, we demonstrate that, while 1D CsI chains form within narrow ∼0.73 nm diameter single-walled carbon nanotubes (SWCNTs), wider SWCNT tubules (∼0.8-1.1 nm) promote the formation of helical chains of CsI 2 × 1 atoms in cross-section. These CsI helices create complementary oval distortions in encapsulating SWCNTs with highly strained helices formed from strained Cs2I2 parallelogram units in narrow tubes to lower strain Cs2I2 units in wider tubes. The observed structural changes and charge distribution were analyzed by density-functional theory and Bader analysis. CsI chains also produce conformation-selective changes to the electronic structure and optical properties of the encapsulating tubules. The observed defects are an interesting variation from defects commonly observed in alkali halides as these are normally associated with the Schottky and Frenkel type. The energetics of CsI 2 × 1 helix formation in SWCNTs suggests how these could be controllably formed.

Original languageEnglish
Pages (from-to)13389-13398
Number of pages10
JournalACS Nano
Issue number8
Early online date9 Aug 2021
Publication statusPublished - 24 Aug 2021

Bibliographical note

Funding Information:
We are indebted to the EPSRC (UK) for support under Grant Nos. EP/N010825/1, EP/M011925/1, EP/M010643/1, and EP/R019428/1. M.G.B. thanks the Russian Government for financial support (Global Education program). We are also indebted to E. Hu for useful discussions regarding Raman and PL spectroscopy.


  • atomic chains
  • carbon nanotubes
  • density functional theory Raman spectroscopy
  • electron microscopy
  • photoluminescence

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)


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