Vibrational properties
Dimer 1, the repeating unit of poly(NVIM), has 28 atoms which
give rise to 3N-6 = 78 normal modes. The experimental FTIR spectrum
of NVIM, and FTIR and Raman spectra of poly(NVIM) are
shown in Fig. 3. Some of the observed Raman and FTIR frequencies
and their calculated counterparts along with their assignments,
and a comparison with earlier study [28] are given in Table 3. Theoretical
values were calculated at B3LYP/6-31+G(d) level and a uniform
scaling factor of 0.9806 was applied [29]. The assignments of
the vibrational modes have been made on the basis of the internal
coordinate analysis implemented in Gaussian03. For the most of
the modes in Table 3, scaled harmonic frequencies differ from
experimental values by 0–10 cm1.