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1.
Opt Express ; 23(21): 27786-94, 2015 Oct 19.
Article in English | MEDLINE | ID: mdl-26480440

ABSTRACT

A novel Dy(3+)/Yb(3+) co-doped PbF2 mid-IR laser crystal was successfully grown using the vertical Bridgman method. Efficient emission at around 3 µm from the crystal was observed under excitation of a conventional 970 nm laser diode (LD). The energy transfer efficiency from Yb(3+) to Dy(3+) in Dy(3+)/Yb(3+):PbF2 crystal is as high as (97.7±0.3)%. It is also found that the Dy(3+)/Yb(3+):PbF2 crystal possesses long fluorescence lifetime (15.4±0.2) ms, high quantum efficiency (95.0±0.3)%, and large emission cross section (1.37±0.11)×10(-20) cm2 corresponding to the stimulated emission of Dy(3+):(6)H(13/2)→(6)H(15/2) transition. Additionally, the phonon energy of the crystal was analyzed by the Raman spectrum. These results indicate that Dy(3+)/Yb(3+):PbF2 crystal may become a promising material for 3 µm solid state lasers under a conventional 970 nm LD pump.

2.
Photosynth Res ; 87(1): 83-103, 2006 Jan.
Article in English | MEDLINE | ID: mdl-16416049

ABSTRACT

This manuscript discusses the photophysical behavior of transition metal complexes of Ru(II) and Os(II) employed in development of light harvesting arrays of chromophores. Particular emphasis is placed on the relationship between the photophysical behavior of complexes having metal-to-ligand charge transfer (MLCT) excited states and the electronic characteristics of bridging ligands used in preparing oligometallic complexes. Examples are presented that discuss intramolecular energy migration in complexes having two distinct MLCT chromophores with bridging ligands that only very weakly couple the two chromophores. In addition, systems having bridging ligands with localized triplet excited states lower in energy than the MLCT state of the metal center to which they are attached are discussed. These systems very often have excited states localized on the bridging ligand with excited state lifetimes on the order of tens of microseconds. Finally, systems having Fe(II) metal centers, with very low energy MLCT states, are discussed. In complexes also containing bridging ligands with low energy triplet states, energy partitioning between the Fe center MLCT state (or Fe localized ligand field states) and the ligand triplet state is observed; the two states relax to the ground state via parallel pathways, but the Fe(II) center does not serve as an absolute excitation energy sink.


Subject(s)
Electrons , Imines/chemistry , Iron/chemistry , Light , Osmium/chemistry , Ruthenium/chemistry , Ligands , Molecular Structure , Photochemistry , Temperature , Time Factors
3.
Chem Commun (Camb) ; (37): 3933-5, 2006 Oct 01.
Article in English | MEDLINE | ID: mdl-17268675

ABSTRACT

We report a simple yet highly efficient route to prepare polymers with a variety of pendant iridium complexes as potential materials in organic light-emitting diodes by employing click chemistry.


Subject(s)
Iridium/chemistry , Light , Organometallic Compounds/chemical synthesis , Polymers/chemistry , Biomedical Engineering , Molecular Structure , Spectrum Analysis
4.
J Am Chem Soc ; 126(50): 16304-5, 2004 Dec 22.
Article in English | MEDLINE | ID: mdl-15600315

ABSTRACT

The photophysical behavior of a series of mono- and trimetallic Ru(II) and mixed Ru(II)/Fe(II) bis-terpyridyl complexes was examined. The complexes have bridging terpyridyl ligands linked by phenylene-vinylene substituents on the terpyridyl. For the complexes bridged by a single phenylene-vinylene, the lowest-energy excited state is metal-to-ligand charge transfer (MLCT), and excited-state decay is on the 1-10 ns time scale. The complexes with two phenylene-vinylene groups have thermally equilibrated excited states that are localized on the phenylene-vinylene bridge and have much longer lifetimes (>200 ns). Remarkably, the trimetallic complex having an Fe(II) terpyridyl center also has a long-lived excited state, despite the fact that low-energy iron-localized excited states exist on the complex.

5.
Chem Commun (Camb) ; (20): 2344-5, 2002 Oct 21.
Article in English | MEDLINE | ID: mdl-12430432

ABSTRACT

The excited state of terpyridine derivatives of phenylene-vinylene fragments chelating Zn(II) show a strong solvatochromism (up to 56 nm) upon preferential solvation by polar solvents of an intraligand charge transfer state.

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