Raman scattering in (CH)x and (CH)x treated with bromine and iodine

Electrochemical polymerization of acetylene on Rh electrodes probed by surface-enhanced Raman spectroscopy

“…It can also be concluded from Table 1 that the main product is trans-polyacetylene. The appearance of a very weak band at 881 cm À1 , a feature of cis-species, indicates that there is only a minor amount of cis-species in the product [20]. As shown in Table 1, the two peaks at around 1082 and 1103 cm À1 in Figs.…”

“…The polymerization mechanism and chemical or physical properties of polyacetylene have been extensively studied by various techniques. Raman spectroscopy has been one of such techniques, as polyacetylene shows the resonance Raman effect in the visible light region [6,11,[18][19][20][21][22][23][24][25][26]28]. It was found that no matter which preparation processes have been used, the obtained films show the characteristic Raman peaks of the trans-polyacetylene at around 1100 and 1500 cm À1 .…”

“…There are a lot of reports on the preparation of polyacetylene, because of its good electrical conductivity and the enhancement of electrical conductivity of many orders of magnitude after dosing [19][20][21][22][23][24][25][26][27][28]40,41]. The polyacetylene can be prepared in organic solutions with various catalysts by either chemical or electrochemical processes and can also be formed by condensing the acetylene molecule under a high pressure.…”

High‐pressure Raman and infrared spectroscopy of polyacetylene

“…1,7 -13 The optical energy gap is about 1.6 eV for trans-PA and 1.9 eV to 2.1 eV for cis-PA, which is well inside the region of the visible wavelength. 6 Lefrant et al 7 were the first to observe the optical resonance effect during Raman measurements with excitation energies close to the energy gap of the cis isomer. In the case of the trans isomer, the shape of the Raman broad bands close to 1100 cm 1 , named 1 (C-C stretch and C-H bending) and 1500 cm 1 , named 2 (C-C stretch), also depends on the excitation energy and, according to Yacoby and Roth, 13 it is generally agreed that the shape of these broad bands is affected by the presence of inhomogeneities in the PA film, related to the distribution of chains with different lengths of the undisturbed conjugated segments, or to varying electron-phonon coupling.…”

Isomerization and Disorder of Polyacetylene Induced by Doping

“…2 b shows the spectrum of a low-quality trans-(CH), in comparison to the spectra A, B, and C. Obviously all spectra A to C are typical for trans-(CH), but the line from the non-resonant mode a t 1291 cm-1 and the high-frequency part of the line for the C=C stretch mode are considerably enhanced only in the spectra for the doped polymer. Further information on the structure of polyacetylene can be obtained from the dependence of the Raman spectra on the excitation frequency [ll, 20 to 231 (dispersion effect). Thus various laser lines have been used for excitation.…”