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Home / All items tagged with x-ray absorption spectroscopy (XAS)

ALS Work Using XAS

In x-ray absorption spectroscopy (XAS), the incident x-ray energy is tuned over a range that will excite core-level electrons. Sharp increases in absorption occur at specific energies, characteristic of the absorbing element. The resulting spectra probe the elemental composition as well as the chemical and electronic structure of the material.

 

A New Way to Tune Emergent Magnetism

Perpendicular magnetic anisotropy (PMA)—where magnetic moments in a thin film preferentially point out of the plane of the film—is an emergent phenomenon of both fundamental and technological interest. A combination of x-ray techniques demonstrate how to tune PMA in transition-metal oxide multilayers. Read more »PPT-icon-35 PDF-icon-35

New Study on Graphene-Wrapped Nanocrystals Makes Inroads Toward Next-Gen Fuel Cells

A powdery mix of metal nanocrystals wrapped in single-layer sheets of carbon atoms shows promise for safely storing hydrogen for use with fuel cells for passenger vehicles and other uses. Now, a new study provides insight into the atomic details of the crystals’ ultrathin coating and how it serves as selective shielding while enhancing their performance in hydrogen storage. Read more »

A Multifunctional Material with Electric-Field Control

Three distinct crystalline phases with different electronic, magnetic, and optical properties were reversibly induced in a material through the insertion and extraction of ions by an electric field at room temperature. Such multifunctional materials are desirable for many applications, from smart windows to spintronics. Read more »PPT-icon-35 PDF-icon-35

Fine-Tuning Oxygen Vacancies with Coherent Strain

Researchers have demonstrated a novel way to systematically strain-engineer oxygen vacancies in complex transition-metal oxide thin films. The work advances our ability to tailor such defects, small changes in which can lead to dramatic changes in material properties such as conductivity and magnetism. Read more »

A Seaweed Derivative Could Be Just What Lithium-Sulfur Batteries Need

Lithium-sulfur batteries have great potential as a low-cost, high-energy, energy source for both vehicle and grid applications. However, they suffer from significant capacity fading. Now, scientists have found that carrageenan, a seaweed derivative, acts as a stabilizer, allowing for more cycling and an extended lifetime. Read more »

Bacterial Symbiont Sequesters Arsenic and Barium in Sponges

Researchers used x-ray fluorescence, spectroscopy, and diffraction to study how populations of symbiotic bacteria can act as a detox organ in a host with no organs. The bacteria, members of the species Entotheonella, accumulate and mineralize large quantities of arsenic and barium in sponges. Read more »

Ptychography of a Bacterium’s Inner Compass

Magnetotactic bacteria (MTB) synthesize chains of magnetic nanocrystals (magnetosomes) that interact with the Earth’s magnetic field like an inner compass needle, simplifying their search for optimum environments. Ptychographic spectra of magnetosomes from a marine MTB provides insight into how these inner compasses form. Read more »

For Better Batteries, Open the Voltage Window

Electrochemical (battery) cells with aqueous electrolytes can be safe, inexpensive, and environmentally friendly, but they are limited by a narrow voltage window. X-ray absorption spectroscopy helps explain why an aqueous Na-ion system with Mn5O8 electrodes has a large voltage window and performs comparably to Li-ion batteries. Read more »

Magnetism Emerges at Wonky Interfaces

Researchers have found a new way to control magnetism at the atomic level that will serve as a model for studying emergent phenomena in other systems. The ability to engineer and tune properties on such small length scales can (eventually) enable us to design exciting new magnetic devices. Read more »