The lowest-energy singlet (1 A') and two lowest-energy triplet (1 A' and 1 A") electronic states of CO2 are characterized using dynamically-weighted multireference configuration interaction (dw-MRCI+Q) electronic structure theory calculations extrapolated to the complete basis set (CBS) limit. Global analytic representations of the dw-MRCI+Q/CBS singlet and triplet surfaces and of their CASSCF/...

A new series of luminescent 1,4-diazatriphenylene (ATP) derivatives with various peripheral donor units, including phenoxazine, 9,9-dimethylacridane and 3-(diphenylamino)carbazole, is synthesized and characterized as thermally activated delayed fluorescence (TADF) emitters. The influence of the donor substituents on the electronic and photophysical properties of the materials is investigated by...

The 364 nm negative ion photoelectron spectra of CF2, CCl2, CBr2, and CI2 exhibit transitions to two different electronic states, the A1 and B1. The CF2 spectrum exhibits well-resolved transitions to both electronic states. In the cases of CCl2, CBr2, and CI2, the spectra exhibit extended, partially resolved vibrational progressions and the two states are overlapped, making a direct determinati...

The singlet-triplet splittings of chlorine-substituted methylenes and silylenes have been studied by using the ab initio generalized valence bond (GVB) dissociation-consistent configuration interaction (DCCI) method. All chlorine-substituted methylenes and silylenes have singlet ground states, with calculated singlet-triplet splittings of 6.0, 20.5, 35.8, and 55.2 kcal/mol for CHCI, CCI2, SiHCI...

We have measured and fitted the kinetics of luminescence of Ag nanoclusters homogeneously dispersed within the bulk of an oxyfluoride glass, with various sample temperatures. The balance equations for the populations of the excited singlet and triplet states of the Ag nanoclusters are proposed and used in this fitting while taking into account inter-system crossing between the singlet and tripl...

Lifetimes of triplet-state molecules and triplet quantum yields are important parameters in photobiology as they determine the generation of singlet-oxygen upon irradiation with visible light. Here we report lifetimes of protoporphyrin IX (pp) in vacuo measured in an ion storage ring. We find that after 532 nm photon absorption, pp(-) (free base and negatively charged carboxylate) and pp(+) (si...

Singlet fission is a photophysical process that has promise for increasing the efficiency of solar cells. The dynamics depend on triplet spin states and can be influenced by external magnetic fields. In 4-electron systems, fission takes an initial singlet state into a superposition of triplet pair states. Direct evidence for this superposition state is provided by quantum beats in the delayed f...

Singlet fission, the splitting of one singlet into two triplets, can potentially increase the efficiency of optoelectronic devices beyond conventional limits. Among the singlet fission molecules discovered to date, two mechanisms have emerged: intraor intermolecular singlet fission. Here we show a combined intrato intermolecular singlet fission mechanism in the model system of diphenyl-dicyano-...

The chemical dynamics of the formation of the i-C4H3(X A 0) radical together with its partially deuterated isotopomers were investigated in eight crossed molecular beams experiments of dicarbon molecules in their XRg electronic ground and in first excited a Pu state with (partially deuterated) ethylene at collision energies between 12.1 and 40.9 kJ mol . The center-of-mass angular distributions...

The longest-wavelength π-to-π* electronic excitations of rhodamine-like dyes (RDs) with different group 16 heteroatoms (O, S, Se, Te) have been investigated. Time-dependent Kohn-Sham theory (TDKST) calculations were compared with coupled-cluster (CC) and equations-of-motion (EOM) CC results for π-to-π* singlet and triplet excitations. The RDs exhibit characteristics in the TDKST calculations th...