Quantitative characterization of SWNT orientation by polarized Raman spectroscopy

A generalized spherical harmonics expanded orientation distribution function (ODF) has been used to study the orientation of SWNTs. A relationship between the second- and fourth-order SWNT orientation parameters and the Raman scattering intensity and depolarization ratio has been established. Only by determining the VV and VH intensities at 0° and 90° to the orientation direction, the second- and fourth-order SWNT orientation parameters can be determined. From the second- and fourth-order orientation parameters, orientation distribution function can be constructed using the maximum entropy formalism.