Excited state relaxation dynamics and up-conversion phenomena in Gd 3 (Al,Ga) 5 O 12 single crystals co-doped with holmium and ytterbium

AbstractThe triplet metal to ligand charge transfer (3MLCT) luminescence of ruthenium (II) polypyridyl complexes offers attractive imaging properties, specifically towards the development of sensitive and structure-specific DNA probes. However, rapidly-deactivating dark state formation may compete with 3MLCT luminescence depending on different DNA structures. In this work, by combining femtosecond and nanosecond pump-probe spectroscopy, the 3MLCT relaxation dynamics of [Ru(phen)2(dppz)]2+ (phen = 1,10-phenanthroline, dppz = dipyridophenazine) in two iconic G-quadruplexes has been scrutinized. The binding modes of stacking of dppz ligand on the terminal G-quartet fully and partially are clearly identified based on the biexponential decay dynamics of the 3MLCT luminescence at 620 nm. Interestingly, the inhibited dark state channel in ds-DNA is open in G-quadruplex, featuring an ultrafast picosecond depopulation process from 3MLCT to a dark state. The dark state formation rates are found to be sensitive to the content of water molecules in local G-quadruplex structures, indicating different patterns of bound water. The unique excited state dynamics of [Ru(phen)2(dppz)]2+ in G-quadruplex is deciphered, providing mechanistic basis for the rational design of photoactive ruthenium metal complexes in biological applications.

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Growth and optical properties of Eu2+/Li+-co-doped SrB4O7 single crystals

Journal of Physics and Chemistry of Solids ◽

10.1016/j.jpcs.2011.01.006 ◽

2011 ◽

Vol 72 (4) ◽

pp. 252-255 ◽

Cited By ~ 9

Author(s):

Zhiwei Jiao ◽

Shaoxia Li ◽

Qingfeng Yan ◽

Xiaoqing Wang ◽

Dezhong Shen

Keyword(s):

Optical Properties ◽

Single Crystals ◽

Co Doped

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Magnetic properties of undoped and Co-doped n-type β–FeSi2.5 single crystals

Journal of Materials Research ◽

10.1557/jmr.2002.0429 ◽

2002 ◽

Vol 17 (11) ◽

pp. 2960-2965 ◽

Cited By ~ 4

Author(s):

E. Arushanov ◽

L. Ivanenko ◽

D. Eckert ◽

G. Behr ◽

U. K. Rößler ◽

...

Keyword(s):

Activation Energy ◽

Magnetic Properties ◽

Magnetic Susceptibility ◽

External Field ◽

Single Crystals ◽

Spin Glasses ◽

Paramagnetic Centers ◽

Temperature Dependent ◽

Paramagnetic Curie Temperature ◽

Co Doped

Results of magnetization and magnetic susceptibility measurements on undoped and Co-doped FeSi2.5 single crystals are presented. The temperature dependence of the magnetic susceptibility of the Co-doped sample in the range of 5–300 K can be explained by temperature-dependent contributions due to paramagnetic centers and the carriers excited thermally in the extrinsic conductivity region. The values of the paramagnetic Curie temperature and activation energy of the donor levels were estimated. It is also shown that the magnetic susceptibility of Co-doped samples cooled in zero external field and in a field are different. This resembles the properties of spin-glasses and indicates the presence of coupling between magnetic centers.

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