Photo-Induced Effects in Mn4+:YAG. Observation of Unusually Efficient Excited State Absorption and a Long–Lived Metastable State

1999 ◽  
Vol 597 ◽  
Author(s):  
Yanong Han ◽  
Lee H. Spangler ◽  
Ralph Hutcheson ◽  
Randy W. Equall
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Excited State Absorption ◽  
Wavelength Region ◽  
Optical Storage ◽  
Electron Configuration ◽  
Valence States ◽  
Wide Range ◽  
Potential Applications ◽  
Long Lifetime

AbstractThe Mn4+ ion has the same d3 electron configuration as Cr3+, but is less stable and can transform to other valence states. Both ions are known to occupy several sites in garnet hosts, giving rise to rather complicated optical spectra and photo-induced phenomena. Here, the spectra of the transient, photo-induced absorption and the emission of Mn4+,:YAG are analyzed over a broad wavelength region (from 450 to 1200nm) and over a wide range of time scales (from ns to minutes). Very large amplitude and extremely broadband excited state absorption are observed. Additionally, a long lifetime, photo-induced species was detected that is likely formed via charge transfer. The demonstrated behavior of this material shows it has potential applications for optical limiting and optical storage.

Fourier Transform Techniques for Measuring Absorption of Transient Species Inoptical Limiting Materials

1999 ◽  
Vol 597 ◽  
Author(s):  
Yanong Han ◽  
Wendi Sonnenberg ◽  
Kurt W. Short ◽  
Amy Hyfield ◽  
Lee H. Spangler
Keyword(s):  
Fourier Transform ◽  
Excited State ◽  
Charge Transfer ◽  
Ultrafast Lasers ◽  
Excited State Absorption ◽  
Spectral Information ◽  
Transient Species ◽  
Rapid Scan ◽  
Wide Range ◽  
Incoherent Source

AbstractWe have developed methods of measuring absorption of transient species utilizing both rapid scan and stepped-scan Fourier transform interferometery that allows a combination of broad spectral coverage (10,000 – 15,000 cm-1 per spectrum), good spectral resolution, and the ability to cover temporal ranges from minutes to nanoseconds. A wide range of pump sources are used including continuous, modulated, ns pulsed, and ultrafast lasers. The probe is provided by a broadband, incoherent source providing large spectral information in each experiment. This capability enables investigation of phenomena such as excited state absorption, charge transfer, formation of metastable species, and others. Extension of the technique to the ps realm is underway and will be discussed.

THE ELECTRONIC STRUCTURE AT ORGANIC–2D MATERIAL HETEROINTERFACES

2021 ◽  
pp. 2140003
Author(s):  
YU LI HUANG ◽  
ANDREW THYE SHEN WEE
Keyword(s):  
Charge Transfer ◽  
Electronic Structures ◽  
Transition Metal Dichalcogenides ◽  
2D Material ◽  
Physical Mechanisms ◽  
Wide Range ◽  
Fundamental Understanding ◽  
Potential Applications ◽  
Metal Dichalcogenides ◽  
Interfacial Charge

Organic–2D material heterostructures have attracted intensive research interest due to their intriguing properties, with a wide range of potential applications in multifunctional flexible electronic and optoelectronic devices. Central to the realization of such devices is a fundamental understanding of the electronic structures at organic–2D material heterointerfaces. The energy level alignment (ELA) at the interface is of paramount importance because it determines the charge transfer barriers between the two materials in contact. In this paper, we discuss the physical mechanisms determining the ELAs, with special attention on interfacial charge transfer at the heterostructures. We review the current understanding of electronic properties at the heterointerfaces formed by the integration of organics with graphene and 2D transition metal dichalcogenides (TMDs), and conclude with a perspective on the future development of organic–2D material heterostructure.

Organometallic ferromagnets

1990 ◽  
Vol 330 (1610) ◽  
pp. 205-215 ◽  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Ground State ◽  
Magnetic Coupling ◽  
Organometallic Complexes ◽  
Electron Configuration ◽  
Ferromagnetic Coupling ◽  
New Materials ◽  
Linear Chains ◽  
Configuration Mixing

Some organometallic solids comprising linear chains of alternating m 8 = 1/2 metallocenium donors, D, and cyanocarbon acceptors, A, i.e. ••• D +*A~*D+*A- * •••, exhibit cooperative magnetic phenomena, i.e. ferro-, antiferro-, ferri-, and meta-magnetism. For [Fe II (C 5 Me 5 ) 2 ]+*[T C N E ]- (Me = methyl; T C N E = tetracyanoethylene) bulk ferromagnetic behaviour is observed below the Curie temperature of 4.8 K. Replacement of Fe III with Fe II , Ni III and Cr III leads to complexes with dia-, antiferro- and ferrimagnetic behaviour, respectively. These results are consistent with a model of configuration mixing of the lowest charge transfer excited state with the ground state developed earlier to understand the magnetic coupling of such systems. The model predicts the magnetic coupling as a function of electron configuration and direction of charge transfer (retro or reverse) and is a useful guide to designing new organic and /or organometallic complexes with cooperative magnetic coupling. To test the model and identify new materials with ferromagnetic coupling new TCNE-based electron transfer salts were prepared.

scholarly journals The Stoichiometry of TCNQ-Based Organic Charge-Transfer Cocrystals

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 993
Author(s):  
Jiaoyang Gao ◽  
Huifei Zhai ◽  
Peng Hu ◽  
Hui Jiang
Keyword(s):  
Charge Transfer ◽  
Physical Properties ◽  
Research Direction ◽  
Research Attention ◽  
Energy Devices ◽  
Donor And Acceptor ◽  
Wide Range ◽  
Significant Research ◽  
Potential Applications ◽  
Organic Optoelectronic

Organic charge-transfer cocrystals (CTCs) have attracted significant research attention due to their wide range of potential applications in organic optoelectronic devices, organic magnetic devices, organic energy devices, pharmaceutical industry, etc. The physical properties of organic charge transfer cocrystals can be tuned not only by changing the donor and acceptor molecules, but also by varying the stoichiometry between the donor and the acceptor. However, the importance of the stoichiometry on tuning the properties of CTCs has still been underestimated. In this review, single-crystal growth methods of organic CTCs with different stoichiometries are first introduced, and their physical properties, including the degree of charge transfer, electrical conductivity, and field-effect mobility, are then discussed. Finally, a perspective of this research direction is provided to give the readers a general understanding of the concept.

Pressure-Induced Wide-Range Reversible Emission Shift of Triphenylamine-Substituted Anthracene via Hybridized Local and Charge Transfer (HLCT) Excited State

2017 ◽  
Vol 6 (3) ◽  
pp. 1700647 ◽  
Author(s):  
Aisen Li ◽  
Zhiyong Ma ◽  
Jinxia Wu ◽  
Ping Li ◽  
Hailong Wang ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Wide Range

scholarly journals Guidelines for Tuning the Excited State Hückel-Baird Hybrid Aromatic Character of Pro-Aromatic Quinoidal Compounds

2020 ◽  
Author(s):  
Sílvia Escayola ◽  
Claire Tonnelé ◽  
Eduard Matito ◽  
Albert Poater ◽  
Henrik Ottosson ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Organic Compounds ◽  
Intramolecular Charge Transfer ◽  
Triplet Excited State ◽  
Computational Tools ◽  
Future Studies ◽  
Aromatic Character ◽  
Wide Range ◽  
New Energy

<p>The present study aims to provide a solid ground for the identification, characterization and controlled design of pro-aromatic quinoidal organic compounds holding conjugated rings with Hückel and/or Baird (singlet and triplet) excited state aromatic character, and expects to become a reference work for future studies on Baird-aromaticity. Concretely, we explore a wide range of compounds with a central conjugated ring of different sizes and symmetric exocyclic substitutions. We employ a combination of different computational tools and we also introduce a new energy-based approach for the quantification of the Baird-aromatic character. </p> <p> </p> The key findings of this study indicate that Baird aromaticity is achieved in pro-aromatic quinoidal compounds having small anionic rings or in electron deficient rings with the proper exocyclic substitution. Low-lying states of these systems show very strong hole/electron overlaps, implying that their aromaticity cannot be related to intramolecular charge transfer.

scholarly journals Guidelines for Tuning the Excited State Hückel-Baird Hybrid Aromatic Character of Pro-Aromatic Quinoidal Compounds

2020 ◽  
Author(s):  
Sílvia Escayola ◽  
Claire Tonnelé ◽  
Eduard Matito ◽  
Albert Poater ◽  
Henrik Ottosson ◽  
...  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Organic Compounds ◽  
Intramolecular Charge Transfer ◽  
Triplet Excited State ◽  
Computational Tools ◽  
Future Studies ◽  
Aromatic Character ◽  
Wide Range ◽  
New Energy

<p>The present study aims to provide a solid ground for the identification, characterization and controlled design of pro-aromatic quinoidal organic compounds holding conjugated rings with Hückel and/or Baird (singlet and triplet) excited state aromatic character, and expects to become a reference work for future studies on Baird-aromaticity. Concretely, we explore a wide range of compounds with a central conjugated ring of different sizes and symmetric exocyclic substitutions. We employ a combination of different computational tools and we also introduce a new energy-based approach for the quantification of the Baird-aromatic character. </p> <p> </p> The key findings of this study indicate that Baird aromaticity is achieved in pro-aromatic quinoidal compounds having small anionic rings or in electron deficient rings with the proper exocyclic substitution. Low-lying states of these systems show very strong hole/electron overlaps, implying that their aromaticity cannot be related to intramolecular charge transfer.

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