Molecular dynamics study of electron-irradiation effects in single-walled carbon nanotubes

Molecular dynamics studies are carried out to investigate electron-irradiation effects in single-walled carbon nanotubes. We have proposed a simulation model which includes the interaction between a high-energy incident electron and a carbon atom, based on Monte Carlo method using the elastic-scattering cross section. The atomic level behavior of a single-walled carbon nanotube under electron irradiation is demonstrated in nanosecond time scale. The incident electron energy, tube diameter, and tube temperature dependences of electron-irradiation effects are studied with the simulation.

Figure 1

Illustration of elastic collision model between an incident electron and a carbon atom. The scattering angle of the electron is determined by the screened Rutherford cross section. The energy transfer from the electron to the carbon atom and the scattering angle of the carbon atom are calculated by the binary collision model.

Figure 2

Schematic views of the deformation process of the (5,5) type of SWNT under $200\mathrm{keV}$ electron irradiation at $300\mathrm{K}$. The irradiation times are (a) 0, (b) 10, (c) 20, (d) 30, (e) 40, and (f) $50\mathrm{ns}$. The rate of the irradiation is $30\text{electrons}∕\mathrm{ps}$.

Figure 3

Ratio of ejected atoms per incident electron after $50\mathrm{ns}$ electron irradiation as a function of electron energy for the (10,10) type of SWNT. The tube temperature is $300\mathrm{K}$. The rates of the irradiation are 20 (▴), 30 (∎), and 40 (●) electrons/ps.

Figure 4

Schematic views of the SWNT after $40\mathrm{ns}$ electron irradiation at $200\mathrm{keV}$. The chiralities of the SWNT are (a) (5,5), (b) (10,10), and (c) (15,15). The rates of irradiation are (a) 20, (b) 40, and (c) $60\text{electrons}∕\mathrm{ps}$. The tube temperature is $300\mathrm{K}$.

Figure 5

Schematic views of the (10,10) type of SWNT after $50\mathrm{ns}$ electron irradiation at $200\mathrm{keV}$. The temperatures of the SWNT are (a) 300, (b) 700, and (c) $1000\mathrm{K}$. The rate of the irradiation is $40\text{electrons}∕\mathrm{ps}$.