Properties of nanopolyacetylene
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Composites of NPA are characterized by:

1. Thermochromic, photochromic, and piezochromic properties;
2. Absence of low-energy peak (charged soliton peak) in photoinduced optical absorption spectra;
3. Extremely low intensity of fluorescence;
4. Passband in near-IR region;
5. Abnormally high intensity of fundamentals in Stokes Raman spectra;
6. Abnormally high sensitivity of fundamentals in anti-Stokes Raman spectra to interactions between nanoparticles;
7. Extremely high stability under laser irradiation.

[1] V.M.Kobryanskii, "Development in Polyacetylene - Nanopolyacetylene", Rapra Review Reports, Reports 114, Vol. 10, Num. 6, (2000). (in PDF)lp

2001. Coherent electron-Lattice vibrations in trans-nanopolyacetylene

Unexpectedly high Raman activity of CC stretching vibrations in an ordered form of PA, NPA was observed. According to our nonlinear model, the partial CC vibrations form a coherent mode in ordered trans-NPA chains due to extended -conjugation giving strong e-ph coupling. The coherent mode is an intrinsic mode of strongly nonlinear electron-lattice system of trans-NPA. The observed long progression of overtones and combinations (or multistage vibrations) is a signature of this nonlinearity. The coherent mode includes many partial CC vibrations and like macrovibration is characterized by long lifetime. In the in-phase region of the coherent mode, the CC vibrations are synchronized over long distances leading to high Raman intensity.

[2] D.Yu.Paraschuk, V.M.Kobryanskii, Physical Review Letters, Vol. 87, pp. 207-402 (2001). (in PDF)lp

2002-2009. Excitation of a breather mode in trans-NPA by sub-five-femtosecond optical pulses

Trans-NPA with degenerate ground state has nonlinear excitation of soliton after photoexcitation, due to the electron-phonon coupling. The excess energy of an excited electron-hole pair over a soliton pair induces breather oscillation characterized by collective stretching vibration of carbon-carbon bonds. Time-frequency analysis of pump probe signal shows that instantaneous frequencies of stretching modes are modulated for 50 fs after excitation and the modulation period is 44 fs. These results match theoretical expectation, what clearly verifies the breather.

[3-1] S. Adachi, V.M. Kobryanskii, and T. Kobayashi, Physical Review Letters,
Vol. 89, pp. 027-401 (2002). (in PDF)lp
[3-2] T. Kobayashi, Adachi, V.M. Kobryanskii, OSA, ME19-1, pp. 91-92 (2002). (in PDF)lp
[3-3] Takahiro Teramoto, Zhuan Wang, Valerii M. Kobryanskii, Takashi Taneichi1, and Takayoshi Kobayashi,
phys. stat. sol. (c) 6, No. 1, 311 314 (2009) (in PDF)lp
[3-4] Takahiro Teramoto, Zhuan Wang, Valerii M. Kobryanskii, Takashi Taneichi, and Takayoshi Kobayashi,
PHYSICAL REVIEW B 79, 033202, (2009), (in PDF)lp
[3-5] Takayoshi Kobayashi, Takahiro Teramoto, Valerii M. Kobryanskii, Takashi Taneichi,
Synthetic Metals 159 (2009) 1751-1756, (in PDF)lp
2003 Stability of NPA at laser irradiation.

It was shown in Raman scattering experiments for free-standing NPA films that long duration irradiation by high intensity laser beams does not lead to film destruction. NPA films with thickness from 0,005 to 1 mm contain 0.5-2 percents PA nanoparticles, dispersed in a matrix of poly (vinyl butyral) were studied. The calculated energy absorbed from laser irradiation exceeds what is required for thermal destruction of NPA films by a factor of 10-1000. The results allow one to suppose that laser irradiation leads to excitation of coherent vibrations of fundumentals in trans-NPA. These are macroscopic quantum vibrations, which are characterized by non-Boltzmann energy distribution. As a result the growth of laser light absorption is accompanied by only very weak heating of NPA films and it can absorb much more laser light than disordered polyacetylene modifications. Questions remain regarding the energy balance for the irradiation experiments. Though it is possible that NPA films undergo coherent energy exchange between nanoparticles located at macroscopic distance form each other.

Compositions of NPA could be used for:
1. Elaboration of optical devices stable under high intensity laser irradiation.
2. Elaboration of shield against laser weapon.

[4] V.M. Kobryanskii, D. Dudis, International Conference - Spectroelectrochemistry of Conducing Polymers, "Optical properties of nanopolyacetylene. Coherence and super stability of freestanding nanopolyacetylene films under resonant and non-resonant laser irradiation." Moscow, October 20-23, 2002. (in PDF)lp


e-mail: kobryan@nanopolyacetylene.com