Low frequency excitation in amorphous acrylic polymers

Low-energy vibrational excitations in polymethylmetacrylate with IR and RAMAN spectroscopy

“…11 To the same vibrations should be assigned and the discussed band in Raman spectrum of PMMA, having a comparable contour and close frequency position of the maximum. 12 A slight broadening of the band and a shift of its maximum towards low frequencies in the spectra of oligomers are apparently caused by an increase in the amplitude and anharmonicity of the librational vibrations in low-molecular analogs of PMMA. The identity of the mechanisms of band formation in the low-frequency IR and Raman spectra of condensed media is confirmed by numerous data.…”

A novel photobleachable polysilane copolymer for optical waveguide fabrication

“…4 and Table 1, however the ratio changed, the birefringence (the difference between n TE and n TM ) of the PMPS‐PBzMA films remained low (around 0.001), and did not change significantly during UV irradiation. Like acrylic polymers15 and polysilanes,16 PMPS‐PBzMA is amorphous. Molecular orientations are offset along its twined flexible backbone, and PMPS‐PBzMA is isotropic, showing low birefringence.…”

Dynamics in the Glassy State and Near the Glass Transition of Amorphous Polymers as Studied by Neutron Scattering

“…The former has been interpreted in terms of a tunneling motion in an asymmetric double well potential proposed by Phillips [23] and Anderson et al [24] independently, but the latter is less understood. Recently, extensive studies on the latter have been performed by inelastic neutron scattering [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] and Raman scattering techniques [40][41][42][43][44][45][46][47]. These studies have revealed that an excess excitation peak exists at 2~3 meV in spectra of all amorphous materials well below the glass transition temperature T g , corresponding to the excess heat capacity at around 10~20 K. This peak is called the "boson peak."…”