The use of confocal Raman imaging spectroscopy and atomic force microscopy for identifying conditions of carbon nanotubes with bent nanotube bundles in the bent state was described. It was found that the tangential G mode on Raman spectra systemically shifts downward upon nanotube bending. The frequency shifts observed in the nanotubes were due to tensile strain of the bending nanotube arrays, which resulted in the loosening of C-C bonds in the outer walls. It was speculated that the frequency shift in Raman spectra was used for fast monitoring of the bending state of the standing carbon nanotube in gas and fluid flow nanosensors.open282
