ZnPSe3_3 as ultrabright indirect bandgap system with microsecond excitonic lifetimes

We report an optical characterization of ZnPSe$_3$ crystals that demonstrates indirect band gap characteristics in combination with unusually strong photoluminescence. We found evidence of interband recombination from excitonic states with microsecond lifetimes. Through optical characterization, we reconstructed the electronic band scheme relevant for fundamental processes of light absorption, carrier relaxation and radiative recombination. The investigation of the radiative processes in the presence of magnetic field revealed spin polarization of fundamental electronic states. This observation opens a pathway towards controlling the spin of excitonic states in technologically relevant microsecond timescales

Fine structure of K\mathrm{K}-excitons in multilayers of transition metal dichalcogenides

Reflectance and magneto-reflectance experiments together with theoretical modelling based on the $\mathbf{k\cdot p}$ approach have been employed to study the evolution of direct bandgap excitons in MoS$_2$ layers with a thickness ranging from mono- to trilayer. The extra excitonic resonances observed in MoS$_2$ multilayers emerge as a result of the hybridization of Bloch states of each sub-layer due to the interlayer coupling. The properties of such excitons in bi- and trilayers are classified by the symmetry of corresponding crystals. The inter- and intralayer character of the reported excitonic resonances is fingerprinted with the magneto-optical measurements: the excitonic $g$-factors of opposite sign and of different amplitude are revealed for these two types of resonances. The parameters describing the strength of the spin-orbit interaction are estimated for bi- and trilayer MoS$_2$.Comment: 14 pages, 10 figure

Interatomic potentials of van der Waals dimers Hg2Hg_{2} and Cd2Cd_{2} : probing discrepancies between theory and experiment

Results of new all-electron ab initio calculations and revisit of experimental studies of the interatomic potentials of lower-lying ungerade excited and ground electronic energy states of the Hg_{2} and Cd_{2} van der Waals complexes are used as probes of discrepancies between theory and experiment. From simulations of the previously and presently measured LIF excitation and dispersed emission spectra new analytical representations of the excited- and the ground-state interatomic potentials are proposed. An inverted perturbation approach was also used to improve the studied interatomic potentials. The comparison of the new ab-initio calculated potentials with the results of the analyses illustrates an improve theory-to-experiment agreement for such a demanding system like Hg_{2} or Cd_{2}

Bound -> free and bound -> bound multichannel emission spectra from selectively excited Rydberg states in the ZnAr and CdAr van der Waals complexes

Multichannel dispersed emission spectra recorded upon a selective excitation of Rydberg electronic energy states in the ZnAr and CdAr van der Waals (vdW) complexes are analysed as a proof-of-concept of the future experimental approach. Simulations of the emission spectra are based on ab-initio calculated interatomic potentials and transition dipole moments (TDMs). Experimental set-up that is under construction along with the experimental procedure are discussed