The enol-keto tautomerism of 2-(2’-hydrophenyl)benzoxazole (HBO) in its metastable triplet states has been studied in fluid, non-polar solution. After laser flash excitation the keto triplet state is populated with high efficiency. The establishment of a ketoenol equilibrium was observed between 55 and 220 K. At low temperatures the rate of this reaction is determined by tunnel effects. The bar...

Photon absorption by carbon nanotubes creates bound electron-hole pairs called excitons, which can exist in spin-polarized triplet or spin-unpolarized singlet configurations. Triplet excitons are optically inactive owing to the weak spin-orbit coupling in nanotubes. This prevents the optical injection of electron spin into nanotubes for spintronic applications and limits the efficiency of photo...

Traditionally, magneto-dielectric effects have been developed by combining ferroelectric and magnetic materials. Here, we show a magneto-dielectric effect from optically-generated intermolecular charge-transfer states in an organic semiconducting donor:acceptor (PVK:TCNB) system. We observe in magnetic field effects of photoluminescence that a magnetic field can change singlet/triplet populatio...

Two-dimensional transition-metal dichalcogenides (TMD) can be combined with other materials such as organic small molecules to form hybrid van der Waals heterostructures. Because of different properties possessed by these two materials, the hybrid interface can exhibit properties that cannot be found in either of the materials. In this work, the zinc phthalocyanine (ZnPc)-molybdenum disulfide (...

In order to identify optimal conditions for singlet fission, we are examining the photophysics of 1,3-diphenylisobenzofuran (1) dimers covalently coupled in various ways. In the two dimers studied presently, the coupling is weak. The subunits are linked via the para position of one of the phenyl substituents, in one case (2) through a CH2 linker and in the other (3) directly, but with methyl su...

in this paper, we calculate theoretically the relaxation rates of hot, thermal and antinodal quasiparticles by using fermi’s golden rule. the transition probabilities at low temperatures express in terms of bogoliubov coefficients, singlet and triplet scattering amplitudes and dimensionless landau parameters. the values of landau parameters may be determined by comparison with the experimental ...

Excited states of singlet and triplet H2Ti(μ−H)2TiH2 have been calculated using multiconfigurational wave functions. The effects of orbital relaxation are determined by optimizing orbitals for all states separately and comparing to state-averaged calculations, and are found to be small. Dynamic electron correlation included through second-order perturbation theory is found to have a considerabl...

We use gate voltage control of the exchange interaction to prepare, manipulate, and measure two-electron spin states in a GaAs double quantum dot. By placing two electrons in a single dot at low temperatures we prepare the system in a spin singlet state. The spin singlet is spatially separated by transferring an electron to an adjacent dot. The spatially separated spin singlet state dephases in...

In light harvesting complex II (LHCII) of higher plants and green algae, carotenoids (Cars) have an important function to quench chlorophyll (Chl) triplet states and therefore avoid the production of harmful singlet oxygen. The resulting Car triplet states lead to a non-linear self-quenching mechanism called singlet-triplet (S-T) annihilation that strongly depends on the excitation density. In ...

The population of the lowest triplet state of thymine after near-UV irradiation has been established, on the basis of CASPT2//CASSCF quantum chemical calculations, to take place via three distinct intersystem crossing mechanisms from the initially populated singlet bright 1pipi* state. Two singlet-triplet crossings have been found along the minimum-energy path for ultrafast decay of the singlet...