Publication Type |
Journal Article |
School or College |
College of Science |
Department |
Physics |
Creator |
Vardeny, Zeev Valentine |
Other Author |
Sheng, C.-X.; Tong, M. |
Title |
Nonlinear optical spectroscopy of excited states in disubstituted polyacetylene |
Date |
2010-05 |
Description |
We used a variety of nonlinear optical (NLO) spectroscopies for studying the excited states order and primary photoexcitations in disubstituted polyacetylene (DPA). The NLO spectroscopies include ultrafast pump-probe photomodulation in a broad spectral range of 0.2-2.5 eV, two-photon absorption in the range of 3.2-4.2 eV, and electroabsorption (EA) in the range of 2.3-4.1 eV. For completeness we also measured the linear-absorption and photoluminescence spectra. We found that the primary photoexcitations in DPA are singlet excitons with three photoinduced absorption (PA) bands, PA0 at 0.6 eV, PA1 at 1 eV, and PA2 at 1.6 eV, respectively, and a stimulated emission band at ~2.5 eV. This is in contrast to other rr-conjugated polymers where the singlet excitons are characterized by two PA bands and a stimulated emission (SE) band. We conclude that in addition to the four essential excited states known to determine the NLO spectra of rr-conjugated polymers, namely, 1Ag, 1Bu, mAg, and nBu; in DPA there is another important complex of states at ~3.3 eV that contains almost degenerate states with odd and even parity symmetries (dubbed here transverse excited state or TES) that is probably reminiscent of the 2Ag state in unsubstituted trans-polyacetylene, which lies in between the 1Bu and mAg of which dipole moment has a strong component perpendicular to the chain direction. In support for this model we found that the depolarization ratio of the EA spectrum drastically changes around the TES from a value of ~2 for һω<3 eV to ~0.5 for һω>3.3 eV. |
Type |
Text |
Publisher |
American Physical Society |
Journal Title |
Physical Review B |
Volume |
81 |
Issue |
20 |
First Page |
205103 |
Last Page |
205101 |
DOI |
10.1103/PhysRevB.81.205103 |
citatation_issn |
1098-0121 |
Language |
eng |
Bibliographic Citation |
Sheng, C.-X., Tong, M., & Vardeny, Z. V. (2010). Nonlinear optical spectroscopy of excited states in disubstituted polyacetylene. Physical Review B - Condensed Matter and Materials Physics, 81(20), 205103-1-8. |
Rights Management |
(c) American Physical Society http://dx.doi.org/[Insert http://dx.doi.org/10.1103/PhysRevB.81.205103] |
Format Medium |
application/pdf |
Format Extent |
412,443 bytes |
Identifier |
ir-main,14776 |
ARK |
ark:/87278/s61g14wb |
Setname |
ir_uspace |
ID |
707332 |
Reference URL |
https://collections.lib.utah.edu/ark:/87278/s61g14wb |