By G.P. Thomas
A new imaging technique employing X-ray diffraction has been developed at the London Center of Nanotechnology that has led to the successful three-dimensional imaging of gold nanocrystals.
The quality of images of nanomaterials has been significantly improved by correcting the imperfections in the X-ray light. This type of imaging can be extended to other nanomaterials as well. Lead author of the study, Dr Jesse Clark from the London Center of Nanotechnology expressed the need to obtain three dimensional images of good quality owing to the significant role taken on by nanomaterials in numerous applications. Dr. Clark also touched upon the limitation imposed by the quality of X-rays and said that they have demonstrated the possibility of producing high quality nanomaterial images with imperfect X-ray sources.
X-ray imaging is deemed to be better than the commonly employed electron spectroscopy to study nanomaterials as X-rays are capable of penetrating the material better than electrons and have the additional advantage of being operable under ambient environment conditions. Since it is difficult to focus X-rays using lens, scientists employ an indirect method called coherent diffraction imaging (CDI) where a computer is used to invert to invert the measured diffraction pattern into an image. Though this method was suggested as early as 1939 by Nobel Prize winner Lawrence Bragg, there was no computer algorithm to fill in the missing diffraction phases at that point of time. The scientists at the London Center of Nanotechnology have shown that the imperfect coherence of X-ray light can be amended by modeling the coherence function. The method can be extended to electron and atom based diffractive imaging and free electron laser imaging.