Credit: N. Abhyankar/NIST
Illustration shows microwaves concentrated in a small region at the center of a newly developed microresonator designed to measure electron spin in extremely small volumes of material. Spotlight shows samples that the device could potentially study, including thin films of graphene, small biological samples and a metallic crystal.
Researchers at the National Institute of Standards and Technology (NIST) have developed a device to detect a quantum property of electrons, known as spin, in extremely small volumes of material and among samples that contain only trace amounts of molecules or ions of interest. The device may enable scientists to accurately measure this fundamental property, which is related to magnetism, in single crystals of biological materials, ultrathin films such as graphene, and other tiny specimens.
Electrons and other subatomic particles behave as if spinning around a central axis, which generates a tiny magnetic field. The spin of an individual electron can only have two values; the electron spin is said to be pointing either ‘up’ or ‘down’ analogous to the north or south poles of bar magnets. In most atoms and molecules, neighboring electrons pair off in such a way that their spins point in opposite directions, canceling each other out and producing a net magnetic field of zero. Atoms and molecules in which some electrons remain unpaired are known as paramagnetic.
Spin measurements of electrons in paramagnetic materials can reveal essential properties of the materials in which they reside, including their molecular and magnetic structure. They can age-date rocks and examine the concentration and reactivity of free radicals and other highly reactive oxygen species—byproducts of aerobic respiration that cause damage to biological tissues, leading to cancer, heart attacks, strokes, and neurodegeneration. The measurements can also reveal the nature of ..
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