The study is focused on the real-time imaging of the nucleation and growth process in the CVD synthesis method.
Ni and Co tips are imaged by FIM during their interaction with light hydrocarbons in order to observe the nucleation and growth of carbon nanotubes in real-time and at the nanoscale. Overlayer chemical compositions are determined using atom-probe techniques (PFDMS) with different time resolutions.
The combination of video-FIM and PFDMS data will provide structure-reactivity relationships along with the identification of the primary building blocks involved in nanotube formation as well as the chemical state of the surface during the ongoing reaction.
Complementary information is obtained by "side-viewing" the metal tips by HRTEM (cooperation with the Fritz-Haber Institute of the Max Planck Society, Berlin).
Particular attention is paid to the question of how chirality is induced during the growth process. Controlling this feature is indeed currently one of the most crucial challenges to take up.
SEM picture of carbon deposit on nickel after exposure to C2H4 at 1000 K.
In a first stage of the project, video-FIM was used to image fast clean-off reactions of the carbon monolayer with hydrogen and oxygen in the presence of high electric fields.
The video sequence shown here demonstrates face-specific effects in field desorption with the occurence of wave-like phenomena finally leading to the layer by layer field evaporation of the clean nickel crystal.