We report detailed longitudinal profiles of four samples of carbon nanotubes (CNT) arrays synthesized using ferrocene-xylene in 850 degrees C Point-to-point analysis of the CNTs grown in growth windows (GWs) were performed using optical microscopy Raman spectroscopy FESEM and high-resolution TEM techniques All samples showed a maximum array height around the middle of their GWs The height profiles comprised a secondary peak/shoulder attributed to evolution of C-2 byproducts The results showed that pyrolytic deposition of amorphous carbon as well as catalytic growth of CNTs strongly depend on the local temperature along the GW It was also observed that the CNT grew longer at the higher flow rate of the carrier gas while the GWs became wider and extended towards the end of the reactor On the other hand the higher liquid flow rate reduced the average diameter and length of the CNTs While residence time was revealed to be important no significant analogy was found between samples with the same feed dilution The termination of GWs was attributed to the inhibition of amorphous carbon as well as temperature drop below similar to 815 C (C) 2010 Elsevier B V All rights reserved