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Zero‐field‐splitting and π‐electron spin densities in the lowest excited triplet state of oligothiophenes
- Source :
- The Journal of Chemical Physics. 105:4441-4447
- Publication Year :
- 1996
- Publisher :
- AIP Publishing, 1996.
-
Abstract
- The electronic properties of thiophene oligomers (nT, n=2–8) have been investigated in the lowest excited triplet state. Theoretical calculations of the zero field splitting parameters and of the π‐electron spin density have been performed and compared with previous experimental EPR results. The calculations are based on a simple π‐electron (one‐electron‐per‐site) model including electron–electron interaction at the extended Hubbard level. Optimized bond lengths result from making them self‐consistent to the corresponding bond orders via Coulson’s relationship. The calculated D values decrease from D=0.0959 cm−1 for n=2 to D=0.0597 cm−1 for n=8, in agreement with EPR data. The measured as well as the calculated E values are rather small. Furthermore, we found that ZFS parameters are affected by the torsion angles between the thiophene rings. The chain length dependence of D can be rationalized comparing π‐electron spin density calculations and computed bond length distortions. These clearly indicate that the triplet excitation reaches a finite extension over about four thiophene rings.
- Subjects :
- Condensed matter physics
General Physics and Astronomy
Electronic structure
Zero field splitting
Bond order
Molecular physics
law.invention
Bond length
chemistry.chemical_compound
chemistry
law
Excited state
Thiophene
Physical and Theoretical Chemistry
Triplet state
Electron paramagnetic resonance
Subjects
Details
- ISSN :
- 10897690 and 00219606
- Volume :
- 105
- Database :
- OpenAIRE
- Journal :
- The Journal of Chemical Physics
- Accession number :
- edsair.doi...........abb4531ee44cead4bb68935b6d29173c