The face of Professor Yuri Oganessian, the only living person with an element named after him, has been shrunk to be smaller than a fibre of wool for a special gift created to mark his visit to the University of Nottingham.
In honour of his visit on the 13thMarch the team in the Nano and Microscale Research Centre (nmRC) have achieved a new record for the smallest periodic table alongside a miniaturised portrait of Oganessian and the creator of the periodic table Dmitri Mendeleev.
Professor Yuri Oganessian is the only living person to have an element in the Periodic Table named after him and is giving a special lecture at the University as part of their celebrations to mark the 150thanniversary of the Periodic Table.
The final design of this special periodic table gift measures just 14 µm ´ 7 µm which is over 6 times smaller than the previous record and the largest dimension is smaller than the diameter of a single fibre of merino wool. The individual lines in the letters are around 30nm which is about the size of the smallest virus. The portraits’ thickness range from 100nm to 1µm meaning they are about 1000 times thinner than a single layer of skin.
Tiny features from electron beams
Dr Richard Cousins is an electron beam lithography technician and created the piece. He explains how it was done: “To create these tiny features a technique known as electron beam lithography was used. Electron beam lithography (EBL) uses a beam of high energy electrons to define a pattern on a thin polymer film, referred to as a resist. The beam of electrons which has a diameter of just a few nanometres (nm) is precisely directed onto the resist-coated silicon chip. When the beam hits the chip it interacts with the resist causing its properties to change. Development of the resist then transfers the pattern onto the silicon chip, which was then further processed to create either the portrait or the periodic table.
The portraits were created on an electron beam lithography tool, using a special resist that allowed us to create a 3D structure by varying the electron dose received by the resist. With the help of colleagues in the school of Physics and Astronomy nanofabrication facilities this pattern was then transferred into the silicon using a method called reactive ion etching. In reactive ion etching different gasses are carefully mixed and formed into a plasma. This plasma is then directed towards the chip where it reacts with the silicon causing it to be removed, by using the resist as a mask we were able to transfer the pattern into the silicon creating a 3D structure.
The process for making the world’s smallest periodic table is similar to that used in screen printing. As described above electron beam lithography was used to create a resist mask that depicted the periodic table. A layer of gold was then deposited onto the chip using thermal evaporation to deposit a thin layer of gold. The evaporated gold only sticks to the area we had defined using EBL and the rest is simply washed of in a solvent leaving behind the desired pattern.”
Yuri Oganessian is a nuclear physicist of Armenian origin who is considered the world’s leading researcher in superheavy chemical elements. The International Union of Pure and Applied Chemistry (IUPAC) announced in November 2016 that element 118 would be named Oganesson to honour him.
Professor Andrei Khlobystov, director of the nmRC, said: “Our Centre has a globally unique combination of equipment, facilities and expertise for nanoscience research, and I am thrilled to have Yuri Oganessian visiting us. Due to his pioneering research the periodic table has no gaps in it now – all periods are full! Every day we use a vast range of materials in the nmRC to study their structures and properties, or to make tiny structures such as in the EBL process which sounds almost magical. It is even more magical to realise that everything in the world is made of 118 elements (or fewer is we disregard the unstable ones), with the last one named after Yuri Oganessian”.
Sir Martyn Poliakoff invited Professor Oganessian to visit the University and said: “Yuri Oganessian is a real superhero of the Periodic Table, an excellent scientist and also a charming person. It’s fantastic that he has accepted our invitation to visit Nottingham and the nmRC’s periodic table is a fitting tribute to mark Yuri’s visit”