The ARES growth substrates consist of silicon micropillar arrays fabricated by reactive ion etching. A single substrate contains a 12×12 array of patches, each patch consisting of a 5×5 array of 10 μm diameter, 10 µm tall silicon pillars (on an SiO2 underlayer) coated with a 10 nmthick Al2O3 support layer (deposited using atomic layer deposition). The catalyst films (0.3 nm Co and 1 nm Fe) were deposited on to the micropillars using magnetron sputtering (Quorum Technologies Q150T ES Plus). In the ARES setup, a high-power (6W, Verdi) laser (532 nm) served as both the heat and Raman excitation source and was directed into a high vacuum sample chamber through an optical window. The Si micropillars were heated up to growth temperatures by regulating the laser power and temperatures were estimated from the redshift of the Raman peak frequency of the Si micropillar. For non-isothermal growth, the laser power was varied manually to lower the growth temperature in a controlled manner (as shown by the temperature profiles in Figure ). During each growth experiment, Raman spectra were collected every 3s and experiments were allowed to proceed until SWCNT growth appeared to cease, as determined by a plateauing of the intensity of the SWCNT Raman peak (G band). Growth profiles were extracted by measuring the G band areas and each profile was fit to a self-exhausting exponential (explained in greater detail in the main text) to extract the maximum growth rates and catalyst lifetimes.