Size effect of nanostructured formations on scattering of optical phonons in pol

2020-01-06 08:43:01

The amorphous spectra PET phonons

责任者: Vettegren, V.I.;Marikhin, V.A.;Kulik, V.B.;Titenkov, L.S. 单位: Ioffe Physicotech. Inst., Acad. of Sci., St. Petersburg, Russia 来源出处: Physics of The Solid State(Phys. Solid State (Russia)),2003/04/,45(4):788-92 摘要: The temperature dependence of the half-width of the infrared (IR) absorption band at a frequency of 971.5 cm-1 in the spectra of poly(ethylene terephthalate) (PET) is investigated for crystallized and amorphous PET samples in which the lengths of trans sequences are approximately equal to 4-7 and 2-3 nm, respectively. The observed increase in the half-width with increasing temperature is explained by inelastic scattering of phonons of stretching vibrations of the macromolecular skeleton by other phonons. The half-width of the band at 971.5 cm-1 in the IR spectra of the amorphous polymer is approximately 1.5 times larger than that in the spectra of the crystallized polymer. This is associated with the violation of the wave-vector selection rules due to a small length of the trans sequences in the amorphous sample 关键词: amorphous state;crystallisation;infrared spectra;nanostructured materials;phonons;polymers;poly(ethylene terephthalate);optical phonons;nanostructured formations;size effect;temperature dependence;infrared absorption band;PET;crystallisation;amorphous PET;phonon inelastic scattering;stretching vibrations;macromolecular skeleton;IR spectra;amorphous polymer;wave-vector selection rules;4 to 7 nm;2 to 3 nm;971.5 cm-1