arXiv subjects

Michael S. Pierce

Publications and source records attributed to Michael S. Pierce.

4 recordsLinked to original sources

arXiv2018

Direct determination of one-dimensional interphase structures using normalized crystal truncation rod analysis

A one-dimensional non-iterative direct method was employed for normalized crystal truncation rod. The non-iterative approach, utilizing Kramers-Kronig relation, avoids the ambiguities due to the improper initial model or the incomplete convergence in the conventional iterative methods. The validity and limitation of the present method are demonstrated through both numerical simulations and experiments with Pt (111) in 0.1 M CsF aqueous solution. The present method is compared to conventional iterative phase-retrieval methods.

cond-mat.other↗

arXiv2017

In situ and non situ surface x-ray scattering studies of in plane Cs+ ordering in Helmholtz planes of Pt(111) surface

In-plane ordering of Cs+ layers in Helmhotlz planes was studied on Pt(111) surface in 0.1 M CsF electrolyte solutions with synchtrotron surface x-ray scattering techniques. The ordering was measured in a new transmission cell, designed for in situ and non situ measurements and high-temperature sample annealing all in the cell without sample transfer steps. At -850 mV vs. Ag/AgCl, (2x2) in-plane scattering peaks were weak under in situ condition and grew rapidly under non situ condition as the surface emersed from the electrolyte. The models for the (2x2) structures are presented and differences between in situ and non situ conditions are discussed.

cond-mat.mtrl-sci↗

arXiv2016

Interaction of Molecular Oxygen with Hexagonally Reconstructed Au (001) Surface

Kinetics of molecular oxygen / Au (001) surface interaction has been studied at high temperature and near atmospheric pressures of O2 gas with in situ x-ray scattering measurements. We find that the hexagonal reconstruction (hex) of Au (001) surface lifts to (1x1) in the presence of O2 gas, indicating that the (1x1) is more favored when some oxygen atoms present on the surface. The measured lifting rate constant vs. temperature is found to be highest at intermediate temperature exhibiting a 'volcano'-type behavior. At low temperature, the hex-to-(1x1) activation barrier (Eact = 1.3(3) eV) limits the lifting. At high temperature, oxygen adsorption energy (Eads = 1.6(2) eV) limits the lifting. The (1x1)-to-hex activation barrier (Ehex = 0.41(14) eV) is also obtained from hex recovery kinetics. The pressure-temperature (PT) surface phase diagram obtained in this study shows three regions: hex at low P and T, (1x1) at high P and T, and coexistence of the hex and (1x1) at the intermediate P and T.

cond-mat.mtrl-sci↗

arXiv2004

Quasistatic x-ray speckle metrology of microscopic magnetic return point memory

We have used coherent, resonant, x-ray magnetic speckle patterns to measure the statistical evolution of the microscopic magnetic domains in perpendicular magnetic films as a function of the applied magnetic field. Our work constitutes the first direct, ensemble-averaged study of microscopic magnetic return point memory, and demonstrates the profound impact of interfacial roughness on this phenomenon. At low fields, the microscopic magnetic domains forget their past history with an exponential field dependence.

cond-mat.other↗