radiative lifetimes
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2021 ◽  
Author(s):  
Xi-Lin Bai ◽  
Xue-Dong Zhang ◽  
Fu-Qiang Zhang ◽  
Timothy C. Steimle

Abstract As a model molecule of actinide chemistry, UO molecule plays an important role in understanding the electronic structure and chemical bonding of actinide-containing species. We report a study of the laser-induced fluorescence spectra of the U16O and U18O using two-dimensional spectroscopy. Several rotationally resolved excitation spectra were investigated. Accurate molecular rotational constants and equilibrium internuclear distances were reported. Low-lying electronic states information was extracted from high resolution dispersed fluorescence spectra and analyzed by the ligand field theory model. The configuration of the ground state was determined as U2+(5f37s)O2-. The branching ratios, and the vibrational harmonic and anharmonic parameters were also obtained. Radiative lifetimes were determined by recording the time-resolved fluorescence spectroscopy. Transition dipole moments were calculated using the branching ratios and the radiative lifetimes. These findings were elucidated by using quantum-chemical calculations, and the chemical bonding was also analyzed. The findings presented in this work will enrich our understanding of actinide-containing molecules.


2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Shiyuan Gao ◽  
Hsiao-Yi Chen ◽  
Marco Bernardi

AbstractPoint defects in hexagonal boron nitride (hBN) have attracted growing attention as bright single-photon emitters. However, understanding of their atomic structure and radiative properties remains incomplete. Here we study the excited states and radiative lifetimes of over 20 native defects and carbon or oxygen impurities in hBN using ab initio density functional theory and GW plus Bethe-Salpeter equation calculations, generating a large data set of their emission energy, polarization and lifetime. We find a wide variability across quantum emitters, with exciton energies ranging from 0.3 to 4 eV and radiative lifetimes from ns to ms for different defect structures. Through a Bayesian statistical analysis, we identify various high-likelihood charge-neutral defect emitters, among which the native VNNB defect is predicted to possess emission energy and radiative lifetime in agreement with experiments. Our work advances the microscopic understanding of hBN single-photon emitters and introduces a computational framework to characterize and identify quantum emitters in 2D materials.


Author(s):  
Shoma Hoshino ◽  
Oji Yamamoto ◽  
Rin Abe ◽  
Daichi Nishimichi ◽  
Yukio Nakano ◽  
...  

2021 ◽  
Vol 154 (7) ◽  
pp. 074707
Author(s):  
Biswajit Bhattacharyya ◽  
Arpita Mukherjee ◽  
Rekha Mahadevu ◽  
Anshu Pandey

2021 ◽  
Author(s):  
Basita Das ◽  
Zhifa Liu ◽  
Irene Aguilera ◽  
Uwe Rau ◽  
Thomas Kirchartz

The term defect tolerance is widely used in literature to describe materials such as lead-halides perovskites, where solution-processed polycrystalline thin films exhibit long non-radiative lifetimes of microseconds or longer. Studies...


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