Polycrystalline tetracene films have been explored using weak ∼ 30 fs visible laser pulses that excite the lowest singlet exciton as well as coherent vibrational motion. Transient difference spectra show a triplet absorption which arises following singlet fission (SF) and persists for 1.6 ns without decay. Adaptive pulse shaping identifies multipulse optimal fields which maximize this absorption feature by ∼ 20%. These are comprised of subpulses separated by time delays well correlated with the period of lattice vibrations suggesting such modes control the yield of SF photochemistry.
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Article Synopsis
- The study demonstrates the detection of singlet fission in tetracene using a field-effect transistor (FET), highlighting its role in producing two triplet excitons from one photon.
- A single crystal FET was developed to provide a clearer understanding of spin-dependent processes under magnetic fields, as opposed to using less ordered materials.
- The researchers successfully manipulated spin-dependent processes to detect changes in magnetoconductance at room temperature by adjusting the voltage and illuminating the FET, linking the observed effects to the singlet fission phenomenon.
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