01835nas a2200169 4500008004100000022001400041245019100055210006900246260007100315300001400386490000800400520106600408100001501474700001801489700003001507856012801537 2013 eng d a1932-744700aDesign and performance aspects of a custom-built ambient pressure photoelectron spectrometer toward bridging the pressure gap: oxidation of Cu, Ag, and Au surfaces at 1 mbar O-2 pressure0 aDesign and performance aspects of a custombuilt ambient pressure a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAR a4717-47260 v1173 a

The critical features of a custom-built laboratory version ambient pressure photoelectron spectrometer (Lab-APPES) are presented. A double front cone differential pumping arrangement and an aperture free design employed in the electrostatic lens regime improve the data collection and data quality. In contrast to the conventional X-ray photoelectron spectrometers (XPS) operating at ultrahigh vacuum (UHV), it is possible to explore the electronic structure of solid surfaces under working conditions or closer to working conditions with Lab-APPES. Especially surface-dependent phenomena can be explored up to 1 mbar pressure and up to 873 K by conventional heating methods and at least up to 1273 K by a laser heating method. Simultaneous XPS and reaction kinetic measurements on solid surfaces make the Lab-APPES an important tool to measure the dynamic electronic structure changes on material surfaces under reaction conditions. The interaction of O-2 with polycrystalline foils of Cu, Ag, and Au from UHV to 1 mbar and up to 773 K has been studied.

1 aRoy, Kanak1 aVinod, C., P.1 aGopinath, Chinnakonda, S. uhttp://library.ncl.res.in/content/design-and-performance-aspects-custom-built-ambient-pressure-photoelectron-spectrometer-001233nas a2200169 4500008004100000022001400041245008900055210006900144260007100213300001400284490000800298520057700306100001900883700002500902700001800927856011800945 2015 eng d a1932-744700aDemonstration of synergistic catalysis in Au@Ni bimetallic core-shell nanostructures0 aDemonstration of synergistic catalysis in AuNi bimetallic coresh a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcAPR a8138-81460 v1193 a

Coreshell bimetallic nanoparticles comprised of gold core and varying nickel shell have been synthesized, and their synergistic effect in catalysis is explored through catalytic hydrogenation of p-nitrophenol and p-nitrothiophenol. A clear evidence for synergism in Au@Ni core-shell nanoparticles having an ultrathin Ni shell (1-2 nm) around a Au core (6-10 nm) resulting in enhanced catalytic activity is observed. The rates observed from a thin nickel shell are higher than monometallic Au or Ni nanoparticles of similar size or with a thicker Ni shell of 6-8 nm.

1 aVysakh, A., B.1 aBabu, Chinchu, Lizen1 aVinod, C., P. uhttp://library.ncl.res.in/content/demonstration-synergistic-catalysis-auni-bimetallic-core-shell-nanostructures-001798nas a2200181 4500008004100000022001400041245012100055210006900176260000900245300001400254490000600268520112600274100002601400700001601426700003001442700001801472856012601490 2017 eng d a2044-475300aDiverse reactivity trends of Ni surfaces in Au@Ni core-shell nanoparticles probed by near ambient pressure (NAP) XPS0 aDiverse reactivity trends of Ni surfaces in AuNi coreshell nanop cOCT  a4489-44980 v73 aA mild temperature sequential reduction method in aqueous medium is reported for the synthesis of Au@Ni nanoparticles with a core-shell morphology. The nickel shell thickness with a gold core in the nanostructure can be tuned from 2 nm up to about 10 nm. Near ambient pressure XPS (NAPXPS) studies under oxygen atmosphere show that Au-80@Ni-20 with an extremely thin nickel shell (similar to 2 nm) follows a distinctly different decomposition pathway of metastable Ni(OOH) species compared to those with larger shell thickness which behave more like individual nickel surfaces. Thus, Ni(OOH) on Au-80@Ni-20 decomposes to metallic Ni at 100 degrees C and is found to resist oxidation at 0.1 mbar oxygen at this temperature. Those with a larger nickel shell thickness behave more like monometallic Ni in terms of their decomposition and oxidation properties. The Au@Ni system with an ultra thin metallic nickel overlayer (2 nm) shows high catalytic activity and selectivity for phenylacetylene hydrogenation under mild conditions which outweighs their monometallic counterparts and those with higher nickel shell thickness.1 aBharathan, Vysakh, A.1 aJain, Ruchi1 aGopinath, Chinnakonda, S.1 aVinod, C., P. uhttp://library.ncl.res.in/content/diverse-reactivity-trends-ni-surfaces-auni-core-shell-nanoparticles-probed-near-ambient02470nas a2200205 4500008004100000022001400041245014900055210006900204260000800273300001400281490000800295520173100303100001802034700001302052700001402065700001802079700002302097700001702120856012702137 2020 eng d a1932-744700aDynamics in amine-functionalized mesoporous hybrid materials probed through deuterium magic angle spinning NMR and molecular dynamic simulations0 aDynamics in aminefunctionalized mesoporous hybrid materials prob cMAR a6154-61700 v1243 a

We present a deuterium magic angle spinning (MAS) NMR study on two widely used hybrid materials (3-glycidyloxy propyl)trimethoxysilane (3-GPTMS) and 3-(trimethoxysilyl)propyl methacrylate (3-MATMS) grafted on SBA-15. Methylene-deuterated diamine as a pendent group is anchored to GPTMS (O3Si-CH2-CH2-CH2-O-CH2-CH(OH)- CH2-NH-CD2-CD2-NH2) and MATMS (O3Si-CH2-CH2-CH2-O-C(N-CD2-CD2-NH2)-C(CH3)=-CH2) postgrafting. Proton and deuterium solid state NMR experiments under MAS were performed at two hydration levels and temperatures ranging from 253 to 315 K. Deuterium spectra were deconvoluted into three A Dr, components with different average quadrupolar parameters: a relatively rigid component arising from local or librational motion of C-H-2(2) corresponding to ``small angle'' jumps, an intermediate dynamic component, and a large amplitude dynamic component. Population ratios of rigid versus dynamic components show that diamine-MATMS is more rigid when compared with diamine-GPTMS at high hydration. The role of the length of the linkers, steric hindrance, grafting concentration, etc. in defining mobility is investigated. Finally, by correlating proton and deuterium MAS NMR spectral analysis, the role of a few water molecules in inducing dynamics of the linkers was investigated. Molecular dynamic (MD) simulations support the experimental analysis. MD simulations indicate different types of mobility arising from the same molecular binding configuration of diamine-MATMS. Dynamics induced by a few hydroxyls on the pore surface accessible to the linker, various molecular conformations, and stabilization of the linker through hydrogen bonding with the surface, derived from MD simulations, are discussed.

1 aVeena, V., S.1 aKavya, I1 aLazar, A.1 aVinod, C., P.1 aAjithkumar, T., G.1 aJayanthi, S. uhttp://library.ncl.res.in/content/dynamics-amine-functionalized-mesoporous-hybrid-materials-probed-through-deuterium-magic