in the octahedral plane, while above 90-100 cm -1 (depending on the presence of bromide or iodide) the in-and out-of-plane Pb-Br bond stretching gives the dominant contribution to the Raman yield. By the analyses of Raman bands at the different chain lengths some indication about the role of the organic moieties can be derived. We performed a series of best-fitting procedures in order to derive band parameters, first of all the peak position, for all the reported spectra. As an illustrative example, Figure shows the best fitting curve obtained for the Raman spectrum of (C8H17NH3)2PbBr4 sample. We used in this case a superposition of five lorentzian curves. Since at RT these bands are the convolution of several vibrational modes, the derived parameters can be used only for a qualitative analysis. This is particularly true for the low energy part of the spectrum where bending and twisting modes can give origin to several contributions. We focused our attention on the behavior of the Raman band peaked at around 120 cm -1 . This Raman band is due to the symmetric Ag mode caused by the stretching -both in and out of plane -of the Pb-I and Pb-Br bond. The energy of the phonon mode remains approximately constant for n = 6, 8 and 10.