Nanoscale Physics

About Possible Mechanisms of Nanoconductivity in Polymethines: The Charge Solitons at Weak External Fields

Vasylyuk S.V.1, Suprun A. D.1, Shmeleva L.V.1
1Taras Shevchenko National University of Kyiv, faculty of Physics. Volodymyrska str., 60, Kyiv, Ukraine. 
E-mail: svetlanafvasylyuk@gmail.com

Linear conjugated compound are excellently important for numerous applications in materials because of their specific electronic, linear and non-linear optical properties [1-3]; also, they are favourite model molecules to verify the new theoretical approach and to study of the dependence of the electron structure in the ground and excited states as well as the nature of the electron transition on an extension of the conjugated chain, symmetry, total charge, topology of terminal groups, etc. [4,5]. The particular interest was attracted by the charged -electron systems; the cationic and anionic polymethine dyes are the famous examples, including the well-known cyanines [1,4,5]. The most applied feature of the polymethine dyes concerns their ability to absorb and emit the light in the visible and near IR spectral region; they exhibit highly intensive and comparatively narrow absorption and fluorescence band. This unique spectral property is found to be due to specific electron distribution in the chromophore and equilibrium molecular geometry in the ground and excited states of the polymethine dye ions. According to present point view, an injection of the electron or hole in the highly-polarized collective system of -electrons causes the appearance of the so-called solitonic level (impurity level) in the energy gap and the considerable shift of the both conductive band bottom and valence band top [1-5]. 
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