arXiv subjects

Amgalanbaatar Baldansuren

Publications and source records attributed to Amgalanbaatar Baldansuren.

3 recordsLinked to original sources

arXiv2015

EXAFS Experiments on Local Structure of NO Adsorbed on Supported Silver Clusters

In-situ EXAFS experiments were performed at the Ag $K$-edge after adsorbing NO on the hydrogen reduced silver cluster. The coordination parameters, i.e. inter-atomic distance, coordination number and Debye-Waller factor were derived from a three-shell fitting model including a split Ag-Ag shell and a single Ag-O(N) shell. The multiple-shell fitting proved that the reduced silver cluster underwent a slight change in the local structure. After co-adsorbing NO and oxygen, the difference file fitting technique was used for isolating each of the first Ag-Ag(1) and Ag-O(N) shell contributions to the EXAFS spectra filtered in R-space of Fourier transform.

cond-mat.mtrl-sci↗

arXiv2015

Structure and magnetic properties of six-atom silver clusters supported on LTA zeolite

12\% (wt.) silver containing catalysts were prepared by aqueous ion-exchange of Ag$^+$ against Na$^+$ in NaA zeolite. Hydrogen reduction leads to the formation of silver clusters. The results of X-ray absorption spectroscopy experiments at the Ag $K$-edge using direct {\it in-situ} reduction yield a Ag-Ag coordination number of 4.00, which is compatible with a quite mono-disperse structure of ca. six-atomic clusters. $<$ 0.1\% of them is EPR active, revealing isotropic parameters with six equivalent silver nuclei. The magnetic susceptibility in a temperature range of 1.8 K to 300 K exhibits Curie-Weiss behavior, with a magnetization up to $\approx$ 0.81 $μ_{\rm B}$ per Ag atom, dependent on reduction history. Thus, the overall magnetization reveals many more unpaired electrons than are observed by EPR, but is still less than a single unpaired electron per atom on average. This suggests that a mixture of diamagnetic, EPR active spin-1/2 and EPR silent high-spin species is present. Interestingly, neutral free Ag$_6$ clusters were predicted by theoretical calculations to be diamagnetic and of planar triangular geometry ({\it Phys. Rev. A.} {\bf 75} (2007) 063204).

cond-mat.mtrl-sci↗

arXiv2015

Electron Spin Relaxations in Biological [2Fe-2S] Cluster System

The phase coherence relaxation times as long as $T_2\sim830-1030\pm20$ ns were measured for the [2Fe-2S] cluster in the intrinsic protein environment. This relaxation corresponds to a relatively long lasting coherence of the low-spin $S=1/2$ state. For this biological cluster, the phase coherence relaxation time was significantly affected by the nuclear hyperfine interactions of $^{14}$N with $I=1$. After labeling the cluster environments uniformly with the $^{15}$N isotope, $T_2$ exceeds $\sim1.1-1.4\pm0.1~μ$s at the canonical orientations. This is already an order of magnitude longer than the duration of a single-spin qubit manipulation $\sim10-100$ ns. The transient nutation experiment corresponds to the coherent manipulation of the electron spin.

q-bio.BM↗