Reaction temperatures and time are probed to get the optimal fluorination conditions in order to produce C2F carbon nanotubes. Possible fluorotube structures are optimized with molecular mechanics calculation. Results show that fluorines would like to add along the circumference of the tubes instead of going down the tube axis. The (1,4) isomer has the lower total steric energy (TSE) between the two proposed fluorotube structures, but the energy difference is small. Scanning tunneling microscopy has been used for atomic scale imaging of the fluorotubes. Significant band features are seen on fluorotubes, not on pristine carbon nanotubes. Butylated tubes have also been investigated by STM imaging. Instead of bands, relatively large, distinct features with spacing of about 50 A are observed. Both theoretical and experimental results indicated the (1,4) isomer with bands around the tubes should be the preferred structure.