Talos TEM operated at 200kV in STEM mode. Samples appropriate for STEM imaging were prepared by depositing a 0.3nm Co film onto 8nm silicon dioxide TEM windows (without the alumina diffusion layer to retain good image resolution). The electron-transparent windows were annealed in a continuous flow of gas and either isothermal or non-isothermal conditions for 5 min, as described in the thermal CVD growth protocols. and their subsequent evolution under isothermal and non-isothermal conditions. The nonisothermal growth cooling period induces greater particle formation and hence, higher nanotube yield.