Showing papers by "S. Roth published in 1983"
TL;DR: In this paper, the free drift time of photogenerated carriers was found to be τfd <10−9sec, and the amount of collected charge was reduced to picoseconds so that the relaxation of electrons and holes into mobile solitons and anti-solitons is questionable.
26 citations
TL;DR: In this paper, the collinear magneto-and coaxial Corbino resistance of iodine doped polyacetylene have been measured at 4.2 K for doping levels from 7% to 30%.
16 citations
TL;DR: In this article, low temperature ESR spectra of cis-rich and trans-rich polyacetylene, lightly doped with pentafluorides (AsF5, SbF5) exhibit two clearly distinguishable ESR lines.
Abstract: Low temperature ESR spectra of cis-rich and trans-rich polyacetylene, lightly doped with pentafluorides (AsF5, SbF5) exhibit two clearly distinguishable ESR lines. Detailed studies of these two lines as a function of temperature, doping concentration and microwave power indicate that one of these lines originates from localized spins, the other from conduction electrons. The concentration of the “localized spins”, generally speaking, decreases with doping. The Pauli-like susceptibility associated with the conduction electrons changes from 1.5×10−7 to 15×10−7 emu·cm3/mole for various doping levels and correlates with the conductivity of the same samples. The longitudinal relaxation time of the localized spins in doped trans-rich was found to beT1≅100 μs at low temperatures, consistent with values of others in undoped trans rich. The temperature dependence of the homogeneous transverse relaxationT2 of the localized spins in doped trans-rich polyacetylene is similar to that of undoped trans polyacetylene. These facts show that the localized spins originate from undoped regions of the doped polyacetylene, perhaps due to inhomogenous doping. Our results are consistent with either formation of metallic islands, or, probably more, with impurity band conduction in strongly disordered semiconductors.
12 citations
TL;DR: Des experiences electriques, magnetiques et optiques dans le polyacetylene sont recensees and des resultats nouveaux sont presentes concernant l'isomerisation cis-trans par dopage AsF5 (etude Raman) ; the coexistence des spins localises and itinerants (experience RPE) meme dans des echantillons dopes doucement ; and la variation en temps (echelle des nanosecondes) de l'effet photoelectrique Des arguments experimentaux prosoliton
Abstract: Des experiences electriques, magnetiques et optiques dans le polyacetylene sont recensees et des resultats nouveaux sont presentes concernant l'isomerisation cis-trans par dopage AsF5 (etude Raman) ; la coexistence des spins localises et itinerants (experience RPE) meme dans des echantillons dopes doucement ; et la variation en temps (echelle des nanosecondes) de l'effet photoelectrique Des arguments experimentaux prosoliton sont critiques et l'avis est exprime qu'il manque des evidences directes de l'existence des solitons mobiles dans le polyacetylene
9 citations
TL;DR: SbF5-doped polyacetylene was studied on samples with dopant concentrations ranging from 0.1 to 8.4 mol%, using 121Sb Mossbauer spectroscopy as mentioned in this paper.
Abstract: SbF5-doped polyacetylene was studied on samples with dopant concentrations ranging from 0.1 to 8.4 mol%, using 121Sb Mossbauer spectroscopy. The spectra reveal the presence of SbF3, SbF5, and SbF-6, respectively. From the relative intensities of the well-separated subspectra we could determine the relative fractions of the three molecular species as a function of dopant concentration.
2 citations
TL;DR: In this article, measurements of the DC conductivity and the 10 GHz microwave conductivity of iodine doped cis and trans polyacetylene in the temperature range from 4.2 K to 300 K are reported.
Abstract: Measurements of the DC conductivity and the 10 GHz microwave conductivity of iodine doped cis and trans polyacetylene in the temperature range from 4.2 K to 300 K are reported. At room temperature no sample shows a frequency dependence ; at low temperatures, however, the microwave conductivity of moderately doped samples is considerably higher than the DC value. From the magnetoresistance at liquid helium temperature an "effective" Hall mobility in the order of magnitude of 102cm2/Vsec is estimated for samples with various iodine concentrations.
2 citations