Carbyne, an infinite carbon chain, has attracted much interest and induced significant controversy for many decades. Recently, the presence of linear carbon chains (LCCs), which were confined stably inside double‐wall carbon nanotubes (DWCNTs) and multiwall carbon nanotubes (MWCNTs), has been reported. In this study, we present a novel method to produce LCCs in a film of carbon nanotubes (CNTs). Our transmission electron microscopy and Raman spectroscopy revealed the formation of a bulk amount of LCCs after electric discharge of CNT films, which were used as field emission cathodes. The LCCs were confined inside single‐wall CNTs as well as DWCNTs. Furthermore, two or three LCCs in parallel with each other are encapsulated when the inner diameter of CNT is larger than approximately 1.1 nm.

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Carbyne is a carbon allotrope whose structure is a one-dimensional chain of sp-hybridized carbon atoms. Carbyne's mechanical and electrical properties, as predicted by theoretical studies, have attracted great interest because they would lead to many promising applications. Thus, much effort has been devoted to the synthesis of carbyne. Long linear atomic carbon chains encapsulated in carbon nanotubes have recently been produced by high-temperature heat treatment of double-wall carbon nanotubes (DWCNTs). Here, we present an alternative approach to produce long linear carbon chains: field electron emission accompanied by electrical discharge from single-wall carbon nanotube (SWCNT) films. Raman spectroscopy and transmission electron microscopy were performed on SWCNT films after the electrical discharge during field electron emission. The results showed that a large number of long linear carbon chains were formed within the SWCNTs and DWCNTs. For DWCNTs with an inner diameter of 0.7 nm, the atomic carbon chains lay directly along the central tube axis. However, for SWCNTs with an inner diameter of 1.0 nm, the encapsulated carbon chains were bent in some places and positioned close to the nanotube wall, away from the central tube axis.

Effects of characteristics of incident waves and of the thickenss of structure on wave reflection by and transmission through a porous structure were studied. Use of an idealized porous structure which is a lattice composed of circular cylinders was made. The relative thickness of structure B/L was found to have appreciable effects on reflected and transmitted wave energies. The reflection coefficient Kr reaches to a maximum of it for B/L of about 0.2 to 0.25, then decreases as B/L increases, and remains approximately uniform for B/L larger than about 0.6. The transmission coefficient Kt, however, decreases nearly exponentially as B/L increases. Measurement of wave height within structure revealed a Dattern of standing waves having a loop at the front face and a node at the rear face of it. That relates to the trend of Kr. Analytical approaches to predict the transmitted wave height, and wave heights before and within porous structures are found to be useful.

Long linear carbon chains (LCCs) encapsulated in carbon nanotubes (CNTs) were produced on a film scale by field emission discharge of CNT films. LCCs inside CNTs were characterized by Raman spectroscopy and transmission electron microscopy. After an electric discharge of a CNT film cathode, long LCCs encapsulated in single-wall CNTs as well as double-wall and triple-wall CNTs were formed in the film. The length of LCCs is longer than 30 nm (i.e., more than 230 carbon atoms). Not only a single LCC but also two or three LCCs in parallel inside a CNT were found. Raman spectra showed prominent peaks, called "LCC bands", in a region from 1790 to 1860 cm −1 originating from longitudinal optical phonons of LCCs. The observation of strong LCC bands are due to resonance Raman scattering, i.e., the excitation photon energies between 1.85−2.54 eV match with energy gaps of the long LCCs inside CNTs.