Friday, June 2, 2023

4033 - X-RAYS - to see atoms?

 

-    4033  -  X-RAYS  -  to see atoms?    Scientists have taken the world’s first X-ray SIGNAL (or SIGNATURE) of just one atom. This groundbreaking achievement was funded by the U.S. Department of Energy, Office of Basic Energy Sciences and could revolutionize the way scientists detect the materials.

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----------------------------   4033   -   X-RAYS  -  to see atoms?

-    Since its discovery by Roentgen in 1895, X-rays have been used everywhere, from medical examinations to security screenings in airports. Even Curiosity, NASA’s Mars rover, is equipped with an X-ray device to examine the materials composition of the rocks in Mars.

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-    An important usage of X-rays in science is to identify the type of materials in a sample. Over the years, the quantity of materials in a sample required for X-ray detection has been greatly reduced thanks to the development of synchrotron X-rays sources and new instruments.

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-    The smallest amount one can X-ray a sample is in “attogram”, that is about 10,000 atoms or more. This is due to the X-ray signal produced by an atom being extremely weak so that the conventional X-ray detectors cannot be used to detect it.

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-    Atoms can be routinely imaged with scanning probe microscopes, but without        X-rays one cannot tell what they are made of. We can now detect exactly the type of a particular atom, one atom-at-a-time,  and can simultaneously measure its chemical state.

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-   Once we are able to do that, we can trace the materials down to ultimate limit of just one atom. This will have a great impact on environmental and medical sciences and maybe even find a cure that can have a huge impact for humankind. This discovery will transform the world.

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-    An iron atom and a terbium atom were both inserted in respective molecular hosts. To detect X-ray signal of one atom, the research team supplemented conventional detectors in X-rays with a specialized detector made of a sharp metal tip positioned at extreme proximity to the sample to collect X-ray excited electrons.

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-    A technique known as synchrotron X-ray scanning tunneling microscopy or SX-STM. X-ray spectroscopy in SX-STM is triggered by photoabsorption of core level electrons, which constitutes elemental fingerprints and is effective in identifying the elemental type of the materials directly.

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-    When X-rays illuminate onto an iron atom, core level electrons are excited. X-ray excited electrons are then tunnel to the detector tip via overlapping atomic/molecular orbitals, which provide elemental and chemical information of the iron atom.  The spectrums are like fingerprints, each one being unique and able to detect exactly what it is.

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-    Using X-rays to detect and characterize individual atoms could revolutionize research and give birth to new technologies in areas such as quantum information and the detection of trace elements in environmental and medical research.

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-    By comparing the chemical states of an iron atom and a terbium atom inside respective molecular hosts, we find that the terbium atom, a rare-earth metal, is rather isolated and does not change its chemical state while the iron atom strongly interacts with its surrounding.

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-    Many rare-earth materials are used in everyday devices, such as cell phones, computers and televisions and are extremely important in creating and advancing technology. Through this discovery, scientists can now identify not only the type of element but its chemical state as well, which will allow them to better manipulate the atoms inside different materials hosts to meet the ever-changing needs in various fields.

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-    They have also developed a new method called “X-ray excited resonance tunneling or X-ERT” that allows them to detect how orbitals of a single molecule orient on a material surface using synchrotron X-rays.

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-    This achievement connects synchrotron X-rays with quantum tunneling process to detect X-ray signature of an individual atom and opens many exciting research directions including the research on quantum and spin (magnetic) properties of just one atom using synchrotron X-rays.

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June 1,  2023                  X-RAYS  -  to see atoms?                       4033

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