7 research outputs found
Hard X-ray magnetochiral dichroism in a paramagnetic molecular 4f complex
Magnetochiral dichroism (MΧD) originates in the coupling of local electric fields and magnetic moments in systems where a simultaneous break of space parity and time-reversal symmetries occurs. This magnetoelectric coupling, displayed by chiral magnetic materials, can be exploited to manipulate the magnetic moment of molecular materials at the single molecule level. We demonstrate herein the first experimental observation of X-ray magnetochiral dichroism in enantiopure chiral trigonal single crystals of a chiral mononuclear paramagnetic lanthanide coordination complex, namely, holmium oxydiacetate, at the Ho L(3)-edge. The observed magnetochiral effect is opposite for the two enantiomers and is rationalised on the basis of a multipolar expansion of the matterâradiation interaction. These results demonstrate that 4fâ5d hybridization in chiral lanthanoid coordination complexes is at the origin of magnetochiral dichroism, an effect that could be exploited for addressing of their magnetic moment at the single molecule level
Possible Conservation of the K -Quantum Number in Excited Rotating Nuclei
The \ensuremath{\gamma} cascades feeding into low-K and high-K bands in Er are investigated analyzing variances and covariance of the spectrum fluctuations. From a large data set of 1 triple coincidences, \ensuremath{\gamma}-\ensuremath{\gamma} coincidence spectra gated by resolved low-lying rotational bands are analyzed. Low-K bands are found to be fed by a much larger effective number of cascades than high-K bands. The covariance between pairs of gated spectra shows that the cascades feeding low-K bands are different from those feeding the high-K bands. The persistence of the K-selection rules for the excited rotational bands within the angular momentum region 30\ensuremath{\Elzxh}\ensuremath{\le}I\ensuremath{\le}40\ensuremath{\Elzxh} is suggested as explanation
Flash and Continuous Photolysis Studies of the Thionitrosyl Complex Cr(CH<sub>3</sub>CN)<sub>5</sub>(NS)<sup>2+</sup> and the Nitric Oxide Analogs. Reactions of Nitrogen Monosulfide in Solution
Lanthanide Modification of CdSe/ZnS Core/Shell Quantum Dots
Lanthanide-modified CdSe quantum dots (CdSeÂ(Ln) QDs)
have been
prepared by heating a solution of CdÂ(oleate)<sub>2</sub>, SeO<sub>2</sub>, and LnÂ(bipy)Â(S<sub>2</sub>CNEt<sub>2</sub>)<sub>3</sub> (bipy
= 2,2â˛-bipyridine) to 180â190 °C for 10â15
min. The elemental compositions of the resulting CdSeÂ(Ln) cores and
CdSeÂ(Ln)/ZnS core/shell QDs show this route to be highly reproducible.
The optical absorption spectra of these composite materials are similar
to those of the unmodified nanocrystals, but the QD-centered band
edge photoluminescence (PL) is partially quenched. The time-gated
emission and excitation spectra of the CdSeÂ(Ln) cores display sensitized
lanthanide-centered PL upon higher energy excitation of the nanocrystal
host but not upon excitation at the lowest energy QD absorption band.
Growth of the ZnS shell led to the depletion of about 60% of the lanthanide
ions present together with depletion of nearly all of the lanthanide-centered
PL. On these bases, we conclude that the lanthanide-centered PL from
the CdSeÂ(Ln) cores originates with Ln<sup>3+</sup>-related trap states
associated with the QD surface