Materials scientists dream of one day being able to place a sample of unknown substance under a microscope and name individual atoms and the structure they form.

That vision of a tool able to analyse a material's atomic architecture or spot atoms that can damage a compound's strength or purity is a step nearer thanks to an exploit by scientists in the United States, the British journal Nature reports yesterday.

They used a transmission electron microscope to analyse a single layer of film made from boron nitride, where they were able to distinguish boron atoms from nitrogen atoms, as well as unwanted atoms of oxygen and carbon.

The technique involves transmission electron microscopy, which sends a narrow beam of electrons through a wafer-thin sample.

Some of the electrons are scattered, depending on the density of the sample.The unscattered ones strike a screen at the bottom of the microscope, creating a "shadow image" formed by interaction between the electrons with atoms in the sample.

The core in transmission electron microscopy dates back to 1931.