Preparation and characterization of monoatomic C-chains: unraveling and field emission

Combined field ion and electron microscopy and mass-spectrometry have revealed the presence of linear carbon chains at the surface of sharpened carbon fibers treated by electric fields of the order of 10¹¹ V m⁻¹. Linear chains attached to carbon tips consisting of more than ten atoms can be produced in situ in a field emission microscope using low-temperature pulsed-voltage field evaporation. The process of field evaporation is sporadic with an anomalously large instant rate of evaporation. Current versus voltage field electron characteristics of monoatomic carbon wires were investigated. By employing molecular dynamics simulation it was shown that atomic C-chains can be produced during the high-field unraveling of nanofibers. These chains are perfectly resolved both in electron and ion modes of the field emission microscope.