Vibration spectrum of pentaerythritol

High pressure study of pentaerythritol: A synchrotron infrared study

“…The ZnSe window in the beamline allows recording of the spectrum for frequencies P600 cm À1 and the IR spectrum consists of vibrations belonging to skeletal modes, internal modes of CH 2 OH and the CH and OH stretching vibrations. The mode assignment was done with the help of the reported lattice dynamical calculation [12] and other Raman and IR spectra [17,18]. Most of the IR mode frequencies of the present study agree fairly well with the Raman and IR experimental data reported earlier [17,18].…”

“…The completely different high-pressure behaviour of CH 4 with PET can be ascribed mainly due to presence of strong hydrogen bonding interaction in the latter. Ramamoorthy et al [12,13] calculated the pressure dependence of the electromechanical and vibrational properties of PET and suggested a possible phase transition at 0.28 GPa with significant increase in the frequencies of the OH and CH modes. PET was also recently investigated in a restricted spectral region of 2700-3800 cm À1 using the FTIR technique upto %25 GPa [14].…”

Synthesis of four‐arm star poly(L‐lactide) oligomers using an in situ‐generated calcium‐based initiator

“…The absence of the characteristic crystalline PLLA bands78 at 926 and 510 cm −1 throughout the course of all the polymerization reactions studied was evidence that, even at the low reaction temperature of 100 °C, neither the polymer or the cyclic dimer were crystalline. Although the reference band does overlap with the CH scissor vibration of pentaerythritol,79 the relative concentration of combined L ‐lactide and PLLA to pentaerythritol, and the respective peak intensities of these bands, any effect caused by this overlap is assumed to be negligible.…”

High-Pressure-Induced Phase Transitions in Pentaerythritol: X-ray and Raman Studies

“…These spectra are characteristic of the molecular configuration, hydrogen bonding, and crystal structure of specific PE phases. The vibrational spectrum of phase I, at ambient conditions, is well-known; ,, it consists of 45 Raman active modes distributed among three different types of symmetry (Γ Raman = 15A + 15B + 15E). As PE undergoes transformation to phases II and III, there are numerous significant changes in the spectra: (i) a new lattice mode occurs at ∼110 cm -1 in phase II and, in addition, several low-intensity modes in phase III, (ii) the C−C stretching mode at ∼1143 cm -1 splits into two in phases II and III, (iii) several nondegenerate modes at 220 cm -1 , 425 cm -1 , and 875 cm -1 split into two or more bands, suggesting a lowering of the crystal symmetry in phases II and III, (iv) in phase III, new peaks also appear in the range from 500 to 700 cm -1 , (v) as shown in Figure , all vibrational peaks, but OH stretching modes, shift toward high frequencies, (vi) there are apparent discontinuities around 4.8 and 7.2 GPa on all modes, (vi) the OH modes exhibit the largest changes in intensity and position, indicating significant modification of hydrogen bonds, and (vii) the OH stretching modes show, in contrast to the other modes, a decrease of frequency with pressure which can be attributed to a strengthening of hydrogen bonding.…”