scholarly journals Radiative and non-radiative transitions of excited Ti3+ cations in sapphire

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Avry Shirakov ◽  
Zeev Burshtein ◽  
Yehoshua Shimony ◽  
Eugene Frumker ◽  
Amiel A. Ishaaya
Keyword(s):  
Temperature Dependence ◽  
Electronic State ◽  
Fluorescence Lifetime ◽  
Radiative Lifetime ◽  
Radiative Transition ◽  
Zero Temperature ◽  
Thermal Phonon ◽  
Radiative Transitions ◽  
Thermal Enhancement ◽  
Radiative Transition Rate

AbstractWe have measured the fluorescence quantum efficiency in Ti3+:sapphire single crystals between 150 K and 550 K. Using literature-given effective fluorescence lifetime temperature dependence, we show that the zero temperature radiative lifetime is (4.44 ± 0.04) μs, compared to the 3.85 μs of the fluorescence lifetime. Fluorescence lifetime thermal shortening resolves into two parallel effects: radiative lifetime shortening, and non-radiative transition rate enhancement. The first is due to thermally enhanced occupation of a ΔE = 1,700 cm−1 higher (top) electronic state of the upper multiplet, exhibiting a transition oscillator strength of f = 0.62, compared to only 0.013 of the bottom electronic state of the same multiplet. The non-radiative rate relates to multi-phonon decay transitions stimulated by the thermal phonon occupation. Thermal enhancement of the configuration potential anharmonicity is also observed. An empiric expression for the figure-of-anharmonicity temperature dependence is given as $$\hat{{\bf{H}}}$$Hˆ (T) = $$\hat{{\bf{H}}}$$Hˆ (0)(1 + β exp(−ℏωco /kBT )), where $$\hat{{\bf{H}}}$$Hˆ (0) = 0.276, β = 5.2, ℏωco = 908 cm−1, and kB is the Boltzmann constant.

scholarly journals An effect of extra compactified dimensions of space in the molecule $$\hbox {NO}_{{2}}$$

2021 ◽  
Vol 75 (12) ◽  
Author(s):  
Hans-Georg Weber
Keyword(s):  
Electronic State ◽  
Vibration Mode ◽  
Radiative Lifetime ◽  
Radiative Transition ◽  
Conical Intersection ◽  
Gravitational Perturbation ◽  
Vibrational Motion ◽  
Stretch Vibration ◽  
Stretch Vibration Mode ◽  
Dimensions Of Space

Abstract The theory of large extra compactified dimensions of space (ADD-model) predicts that gravity may become strong in a compactification space of the size of a molecule and may affect the vibrational motion of a molecule. In triatomic molecules like $$\hbox {NO}_{{2}}$$ NO 2 nuclear dynamics is strongly coupled to electronic dynamics at the intersection of electronic states (conical intersection). We discuss experimental results on $$\hbox {NO}_{{2}}$$ NO 2 which reveal that the collision-free molecule optically excited into a symmetric stretch vibration mode of an electronic state with conical intersection undergoes an irreversible non-radiative transition into an asymmetric stretch vibration mode in combination with a change of the electronic state. We suggest ascribing this irreversible non-radiative transition to a gravitational perturbation on the vibrational motion in $$\hbox {NO}_{{2}}$$ NO 2 . This gravitational perturbation deactivates the upper state of the optical transition. The width of the absorption line is given by the characteristic time of the gravitational perturbation and not by the radiative lifetime of the excited molecular state. Graphical abstract

Judd-Ofelt Analysis of a Dendrtic Type Europium Complex/Silicone Rubber

2011 ◽  
Vol 233-235 ◽  
pp. 1227-1230 ◽  
Author(s):  
Hao Liang ◽  
Fang Xie
Keyword(s):  
Cross Sections ◽  
Silicone Rubber ◽  
Radiative Lifetime ◽  
Radiative Transition ◽  
Optical Devices ◽  
Europium Complex ◽  
Stimulated Emission ◽  
Ofelt Theory ◽  
Intensity Parameters ◽  
Radiative Transition Rate

A dendritic type europium complex/silicone rubber has been prepared. According to the luminescence spectrum, the Judd-Ofelt theory was adopted to calculate the intensity parameters Ω2and Ω4. The total radiative transition rate (640.1 s-1), radiative lifetime (1.562 ms) and the stimulated emission cross-sections (46.19×10-22cm2) of the5D0exciting state have been evaluated. Analysis reveals that the europium (III) chelating polymer is promising for use in optical devices.

Specific features of the temperature dependence of tryptophan fluorescence lifetime in the temperature range of −170–20 °C

2020 ◽  
Vol 393 ◽  
pp. 112435
Author(s):  
Peter P. Knox ◽  
Vladimir V. Gorokhov ◽  
Boris N. Korvatovsky ◽  
Nadezhda P. Grishanova ◽  
Sergey N. Goryachev ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Fluorescence Lifetime ◽  
Tryptophan Fluorescence ◽  
Temperature Range

Temperature Dependence of Tryptophan Fluorescence Lifetime as an Indicator of Its Microenvironment Dynamics

2021 ◽  
Vol 498 (1) ◽  
pp. 170-176
Author(s):  
V. V. Gorokhov ◽  
B. N. Korvatovsky ◽  
P. P. Knox ◽  
N. P. Grishanova ◽  
S. N. Goryachev ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Fluorescence Lifetime ◽  
Tryptophan Fluorescence

TD-DFT calculations of the excited states of metalloporphyrins relevant to organic solar photovoltaic cells

2014 ◽  
Vol 18 (06) ◽  
pp. 475-492 ◽  
Author(s):  
Neha Agnihotri ◽  
Ronald P. Steer
Keyword(s):  
Dft Calculations ◽  
Electronic State ◽  
Excited States ◽  
Photovoltaic Cells ◽  
Oscillator Strengths ◽  
Solar Photovoltaic ◽  
Dft Methods ◽  
Radiative Transitions ◽  
Td Dft ◽  
Triplet Excited States

The molecular orbital energies and symmetries, electronic state energies and symmetries, and orbital compositions and oscillator strengths for one-photon radiative transitions up to an energy of 4 eV have been calculated by DFT and TD-DFT methods for 15 d0 and d10 metalloporphyrins. Data for both singlet and triplet excited states are reported and used to identify potential candidates for use as photon upconverters by homomolecular triplet–triplet annihilation.

Collisional excitation of the formyl radical (HCO) by molecular hydrogen

2020 ◽  
Vol 498 (4) ◽  
pp. 5361-5366
Author(s):  
Paul J Dagdigian
Keyword(s):  
Accurate Determination ◽  
Radiative Transition ◽  
Rate Coefficients ◽  
Cluster Method ◽  
Quantum Scattering ◽  
Close Coupling ◽  
Explicitly Correlated ◽  
Radiative Transition Rate ◽  
Fine And Hyperfine Structure

ABSTRACT This paper addresses the need for accurate rate coefficients for transitions between fine- and hyperfine-structure resolved rotational transitions in the formyl (HCO) radical induced by collisions with the two nuclear spin modifications of H2, the dominant molecule in the interstellar medium (ISM). These rate coefficients, as well as radiative transition rate coefficients, are required for accurate determination of the abundance of HCO in the ISM. Time-independent close-coupling quantum scattering calculations have been used to compute rate coefficients for (de-)excitation of HCO in collisions with para- and ortho-H2. These calculations utilized a potential energy surface for the interaction of HCO with H2 recently computed by the explicitly correlated RCCSD(T)-F12a coupled-cluster method. Rate coefficients for temperatures ranging from 5 to 400 K were calculated for all transitions among the fine and hyperfine levels associated with the first 22 rotational levels of HCO, whose energies are less than or equal to 144 K.

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