Pressure coefficients of Raman modes of carbon nanotubes resolved by   chirality: Environmental effect on graphene sheet
  Studies of the mechanical properties of single-walled carbon nanotubes are hindered by the availability only of ensembles of tubes with a range of diameters. Tunable Raman excitation spectroscopy picks out identifiable tubes. Under high pressure, the radial breathing mode shows a strong environmental effect shown here to be largely independent of the nature of the environment . For the G-mode, the pressure coefficient varies with diameter consistent with the thick-wall tube model. However, results show an unexpectedly strong environmental effect on the pressure coefficients. Reappraisal of data for graphene and graphite gives the G-mode Grueuneisen parameter gamma = 1.34 and the shear deformation parameter beta = 1.34. 
A. J. Ghandour, I. F. Crowe, J. E. Proctor, Y. W. Sun, M. P. Halsall,   I. Hernandez, A. Sapelkin and D. J. Dunstan
cond-mat.mes-hall