What is Synchrotron Light?


The light we see – produced by the sun, by lamps or flames, reflected by objects, captured by our eyes and finally used by our brains to shape and color the world – corresponds only to a tiny fraction of the so-called electromagnetic waves.

However, there are many electromagnetic waves, many types of light that we cannot see, but are produced in the most diverse natural and artificial phenomena. The study of these invisible waves leads not only to the understanding of the phenomena in which they are produced, but also to the development of technologies that use them, for example, to transmit and receive information.

They are radio waves used by Wi-Fi networks, the microwaves used in ovens and mobile phone networks, infrared light used in remote controls, ultraviolet radiation used in artificial tanning, x-rays in CT scans and gamma rays used in therapies against cancer and food sterilization.

These electromagnetic waves are produced when electrically charged particles are accelerated or decelerated. Equipment such as radios, televisions, and cell phones use these properties to transmit and receive information. Circuits present in these devices produce the oscillation of electrons by the conductive material of an antenna. This oscillation produces the radio waves that are transmitted by the equipment. At the receiver side, these same electromagnetic waves will oscillate the electrons in the antenna of the device, reproducing in the internal circuits the signal emitted earlier.

Structure and Properties of Matter

All things, whether living or not, are made of atoms. These atoms are composed of a positively charged nucleus and negatively charged electrons that orbit the nucleus in a stable manner. Each material is made up of bonds between different atoms, and their properties depend on the kind of atom and how they are organized.

The way the atoms of a substance are distributed in space defines the distribution of electrons along the material – its electronic structure – and it is from this structure that the macroscopic properties of a material depend whether it will be rigid or malleable, opaque or transparent, or even conductor, semiconductor or insulation. For example, two materials with completely different properties, such as diamond and graphite, are composed of the same carbon atoms. The only difference is the distribution of these atoms in space.

In order to investigate the properties of various materials it is necessary to know the atoms that compose them and how they are distributed. Just as we use visible light to observe the macroscopic properties of things, their shape and color, it is possible to use the various electromagnetic waves to investigate the structure, composition, and properties of things on the microscopic scale, with much greater precision than our eyes.

Synchrotron Light

Synchrotron Light, or Radiation, is a type of high-flux, high-brightness electromagnetic radiation that extends over a broad range of the electromagnetic spectrum from infrared light through ultraviolet radiation to x-rays. It is produced when charged particles, accelerated at speeds close to the speed of light, have their trajectory deflected by magnetic fields.

The emission of this radiation was predicted theoretically for the first time by the Ukrainian Dmitri Iwanenko and the Russian Isaak Pomeranchuk in 1944, and in 1947 the first observation occurred in General Electric’s research laboratories. It was performed on a particle accelerator of the synchrotron type, with accelerated electrons up to 99.997% of the speed of light.

In a synchrotron accelerator, the charged particle beam is guided in circular orbits by a set of electromagnets. The magnetic field produced by the electromagnets can be varied in time and acts in a synchronized way on the particles, which at each turn have higher velocities and, therefore, higher energies. From this synchronous action comes the name synchrotron accelerator and it is due to this type of accelerator in which it was first observed that the synchrotron radiation received its name.

Later, in 1956, in a synchrotron accelerator of the University of Cornell, USA, the first spectroscopy experiments were carried out in the ultraviolet region with the use of the radiation produced in the accelerator. Thus was started the use of the synchrotron light as a tool for the study of the composition and structure of materials.

The synchrotron light is capable of penetrating matter and reveal characteristics of its molecular and atomic structure. The broad spectrum of this radiation allows researchers to use the most suitable wavelengths for the experiment they wish to perform. While the high flux and the high brightness allows faster experiments and the investigation of very small details, with spatial resolution of nanometers.

With the synchrotron radiation, It is also possible to monitor the temporal evolution of processes that take place in fractions of a second in a wide range of temperature and pressure conditions.