Atoms in small particles of metals move between each other within a blink of an eye, Indian Institute of Technology, Madras have found. Atoms in metals such as gold and silver practically stay at their locations for eternity which make them stable and noble. Chemical and physical processes do not move atoms between particles easily, which explains their stability. However, in nanometre scale particles.
The research was undertaken by Papri Chakraborty, Research Scholar, IIT Madras and her colleagues under the direction of Professor T Pradeep and Chair Professor Deepak Parekh from the Department of Chemistry, IIT Madras.
In the experiment, researchers prepared 1 nanometre particles of silver composed of 25 atoms, protected with molecules called ligandsSuch protected metal particles are called clusters and they are made by solution chemistryTo test the hypothesis of atom transfer, researchers made identical 25 atom clusters with two isotopes of silver (107Ag and 109Ag)
Isotopes are elements with the same atomic number but different atomic masses, and they are identical in chemical propertiesCommon examples are hydrogen (H) and deuterium (D), which are isotopes of hydrogen with same chemical properties However, they have different atomic masses H2O and D2O are waters with the same chemical properties, formed with hydrogen and deuterium
The two isotopes of silver
In isolated state, Ag25 made of 107Ag isotope and Ag25 made of 109Ag isotope are equivalent in chemical properties,They have the same colour, reactivity and structure, but different molecular massesIn an instrument called mass spectrometer, these two clusters show different masses,However, upon mixing these two clusters in solution and measuring the mass spectrum in solution, researchers found that the parent clusters disappeared completely and a new cluster of 25 atoms (mixture of 107Ag and 109Ag atoms) emerged.This was identical to the formation of a molecule of HDO from H2O and D2O when they both were mixed.