PCseminarabstr_190107
Carbyne by definition is an infinite linear chain of carbon atoms that forms the truly onedimensional allotrope of carbon. It is a polyyne with alternating single and triple bonds originating from a Peierls distortion. This bond-length alteration dominates the electronic and vibronic structure of carbyne and opens up a direct band gap. The exploration of carbyne and its properties, however, has long been hindered by its extreme chemical instability and short chain lengths far below the threshold of 100 atoms for which finite linear carbon chains mimic the properties of carbyne. A breakthrough was achieved in 2016 with the synthesis, stabilization and study of individual long linear carbon chains comprising of thousands of atoms inside double-walled carbon nanotubes. [1]
In this talk, I will present our recent studies of individual pairs of double-walled carbon nanotubes and encapsulated linear carbon chains by tip-enhanced Raman spectroscopy [2]. We reveal that the nanotube host, characterized by its chirality (diameter and electronic structure), determines the electronic and vibronic structure of the confined chain. By choice of chirality, the bond-length alteration and hence the fundamental bandgap of the confined chain is tunable by ∼0.6 eV. We find no length dependence of the chain’s properties, making long linear carbon chains confined in nanotubes a close to perfect representation of carbyne. Wavelength dependent Raman measurements provide first insights into the dynamics of the chain’s excited electronic state.[3] Finally, I will discuss the current limitations in studying this exciting new material and provide an outlook on future directions.
[1] Shi et al. Nature Materials 2016, 15(6), 634-639.
[2] S. Heeg et al. Nano Letters 2018, 18(9), 5426-5429.
[3] S. Heeg et al. Carbon 2018, 139, 581-585.