We observed similar trends in the growth kinteics for Tf = 740 ºC. The measured yield, max. growth rate and lifetime are maximized for similar Δtc (~10 s), but at a lower ΔT compared to Tf = 680 ºC -now between 125 and 175 ºC. We note that we also performed growth experiments where the temperature was increased, for example starting at 680 ºC and going up to various temperatures (Ti < Tf) over similar time intervals. While there was a small increase in yield when the temperature difference was small (< 50 ºC), this increase was definitely not as much as in the non-isothermal growths where Ti > Tf. We attribute this lowering of yield due to catalyst coarsening and deactivation at higher temperatures. Figure shows scanning electron microscope (SEM) images from two representative micropillars, highlighting the differences between isothermal and non-isothermal growth. The nonisothermal growth clearly has a higher density of CNTs (Figure ) compared to the isothermal growth (Figure ). The Tf in the non-isothermal growth in Figure was set to 740 ºC to match the growth temperature (Ti = Tf) for the isothermal growth in Figure . The corresponding RBMs displayed in Figure (obtained by averaging the ex situ Raman maps collected over the two micro-pillars with 514.5 and 633 nm excitation) have similar frequencies in both sets of data, with subtle differences in relative intensities between the isothermal and non-isothermal growths: the slightly higher intensity of the lower frequency RBMs (below 200 cm -1 ) in the isothermal growth suggests a higher amount of larger diameter CNTs.