Context: Scientists, for the first time, have identified an element by X-raying a single atom of a material.
The experiment
- X-rays are an important way to identify the type of material. Until the recent experiment, the minimum sample size required was roughly 10,000 atoms.
- The minimum amount of material was required as an atom’s response to being hit by X-rays can be very weak. Hence, the more atoms, the better detectors can pick up on their response.
- For the experiment, the scientists used a method called synchrotron X-ray scanning tunnelling microscopy or SX-STM. The scientists modified a conventional X-ray detector to add a sharp metal tip that would be moved to be extremely close to a sample (as close as 0.5 nanometres from the atom). This is to improve the detector’s ability to record any signals from the atom.
- The sample’s atom was hit with X-ray photons. The electrons in the atom absorbed only photons of certain frequencies. Using a spectroscope, the team determined which frequencies had been absorbed and hence, identified the element. (Every element has a unique absorption spectrum which can be used to identify it).
Significance:
- Identification of a material using only one atom can revolutionise research in material science, quantum mechanics, and other areas.
- The study also characterised the chemical states of the atoms and will help understand their properties better, which would help researchers manipulate the atoms to greater precision.
About X-rays
- X-Rays or X-radiation is a form of high-energy electromagnetic radiation. They have a wavelength ranging from 0.01 to 10 nanometres, frequencies in the range 3 × 10^19 Hz to 3×10^16 Hz and energies in the range of 100 eV to 100 keV.
- X-rays are generated when high-energy electrons interact with matter. X-ray photons carry enough energy to ionize atoms and disrupt molecular bonds.
- A very high radiation dose of X-ray over a short period causes radiation sickness, while lower doses can give an increased risk of radiation-induced cancer.
Applications:
- X-rays are used in checking for fractures (broken bones), spotting pneumonia (chest X-rays), spotting cancer (Mammograms) and detecting tumours.
- Ionizing capability of X-rays can be utilized in cancer treatment to kill malignant cells using radiation therapy.
- X-rays have much shorter wavelengths than visible light, which makes it possible to probe structures much smaller than can be seen using a normal microscope. This property is used in X-ray microscopy to acquire high-resolution images, and also in X-ray crystallography to determine the positions of atoms in crystals.
- X-rays are also used for material characterization using X-ray spectroscopy.
- X-rays can travel through a vacuum (propagate through empty space without requiring a medium). This property allows X-rays to be used in space exploration and research conducted in vacuum chambers.
- X-rays are used in security systems, such as airport scanners, to detect objects hidden within luggage or on a person’s body.
