Archived project

polyacetylen vibrational study

Updates
0 new
0
Recommendations
0 new
0
Followers
0 new
1
Reads
0 new
10

Project log

Eric Perrin
added 2 research items
In this paper, we present an “in situ” experimental study of (CH)x doped electrochemically with potassium at different doping levels. We have used the Resonance Raman Scattering (RRS) technique to probe the (CH)x electrode during doping and dedoping cycles. Starting with a cis-rich (CH)x film, we gradually observe a decrease of the cis isomer content in the polymer film until a doping level y of about 4 %. Then, the well known new modes induced by doping at 1260 and 1560–1600 cm−1 are observed together with those characteristic of trans-(CH)x. They become prominent for y ⩾ 10%. Upon dedoping, the new Raman induced modes are seen until a concentration of 2.5 % for λL = 676.4 nm. All these results are completely correlated with the behavior of the EPR line width, ΔHpp, as a function of the dopant concentration level. Experimental data are interpreted in terms of different doped regions, in which different phases exist in the polymer.
New experimental results of polarized Resonant Raman Scattering (RRS) spectra of fully oriented cis-rich (CH)x films for the excitation wavelengths 676.4 and 600 nm are presented together with the theoretical interpretation. The three Raman active bands due to the totally symmetric vibrational modes of cis-(CH)x are observed only in the / / / / polarized spectrum, indicating that the films are fully oriented. The contribution of the Raman active vibrational modes of the trans segments is observed in all polarized spectra and for both incident wavelengths. Also, we report the RRS spectra of the same sample thermally isomerized, without stretching, for λL = 676.4 nm and λL = 457.9 nm. We find that the depolarization ratios of the Raman bands due to the vibrational modes of trans-segments are much higher after isomerization than for an usual stretched trans (CH)x sample.