Nature is abundant with crystals. Gemstones, a common example of crystals, are mentioned in the oldest pieces of history known to us. Other forms of crystals include the graphite, snowflakes and grains of salts. Crystallography is the study of crystals. Crystals have a characteristic arrangement of atoms. For instance, the element carbon depending on the arrangement has numerous forms such as the common graphite used in pencils (known as lead) and glittering diamond.
The science of crystallography enables us visualise the arrangements of atoms and thereby zero onto the structure of matter. Atoms are very small and hence they cannot be observed directly using an optical microscope. One needs indirect techniques to zoom into the structure of matter. X-rays provide one such technique and have contributed more than any other to our understanding of the structure of matter over the last century. It is to recall that x-rays were discovered in 1895 and is now a common diagnostic tool in medicine. This is so, because x-rays can pass through human bodies and form images on photographic plates.
The science of crystallography before the invention of x-rays relied on the shapes of crystals. From the shapes of the crystals the packing of the atoms was guessed but could not be established. In 1912 it was realised that x-rays passing through crystals form images on photographic plates and these images would give a clear position of the atoms within the crystals.
This discovery revolutionised the world of crystallography. The x-rays were extensively used to study a variety of crystals and their three dimensional structures were obtained. The x-ray studies of crystals were immediately recognised by two Nobel Prizes: Max von Laue (1914) and the father and son duo of William Henry Bragg and William Lawrence Bragg (1915). These two Nobel Prizes in physics were followed by several more bringing the count to: Physics: 8; Medicine: 5 and Chemistry: 10.
International year of crystallography postal stamp
As per the trend the count is expected to increase. In the last hundred years, crystallography has become the leading technique for studying the atomic structure and related properties of materials. X-ray crystallography has enabled us to understand the structure of proteins. This knowledge of the structure of the protein is vital in designing new drugs. Many new materials have been developed based on the insights gained from the structure of matter. Examples include the materials used in computer memory cards to flat television screens, cars and aeroplane components.
At its Sixty-Sixth Assembly on 3rd July 2012, following a proposal from Morocco, the General Assembly of the United Nations adopted the resolution that 2014 should be the International Year of Crystallography (IYCr 2014). This is to commemorate the centennial of x-ray diffraction and related discoveries. The IYCr 2014 was launched at the United Nations Educational, Scientific and Cultural Organisation (UNESCO) headquarters in Paris, during a two-day opening ceremony from 20-21 January 2014. The year-long celebration aims to strengthen international collaboration and increase public awareness of crystallography with a series of conferences, exhibitions and educational activities taking place throughout 2014.
On 30 January 2014, the Department of Posts India brought out a commemorative stamp on the IYCr 2014. The commemorative stamp depicts a diamond, which is known for hardness and the structure of curcumin, a constituent of turmeric known for its medicinal value, as determined by x-ray crystallography.
The stamp was released by M. S. Ramanujan, Chief Post Master General, Karnataka, during a function at the Indian Institute of Science (IISc), Bangalore.
The world of science is passing through an epoch marked with anniversaries and celebrations. Crystallography is synonymous with structure of matter and x-rays. The year 2014 is being celebrated as the International Year of Crystallography. Light has been at the helm of observational/ experimental sciences. The year 2015 has been declared as the International Year of Light and Light-based Technologies. Both the events are a time to recognise the place of crystallographic and photonic techniques in our lives.
[SAMEEN AHMED KHAN teaches in Engineering Department, Salalah College of Technology (SCOT) Salalah, Sultanate of Oman. Email: rohelakhan@yahoo.com]