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Seeing is understanding.

An Overview of Synchrotron Light

A synchrotron acts like a giant microscope. Intense beams light are generated to help scientists understand the nature and structure of molecules and materials.

The Canadian Light Source will be one of the most powerful in the world, producing synchrotron light that is millions of times brighter than sunlight. This new research tool at the University of Saskatchewan will help to find solutions to challenges in health, the environment, and advanced materials.

What is light and what does it do?

Light is energy that travels in waves. Visible light is the small portion of the electromagnetic spectrum that can be seen with human eyes The spectrum is composed of varying energies of light that have different wavelengths

The length of the wave of light, or wavelength, is very important to the scientist. To examine a material using some synchrotron techniques, the wavelength must be the same size or smaller than the material being examined. Some wavelengths are like specialized X-rays that can "see through' some materials.

The data produced when synchrotron Light interacts with various materials is analyzed to produce images and charts that can illustrate such things as the relationships of atoms within molecule.

An Overview of Beamline Operations

Synchrotron Analysis of Molecules

Beams of synchrotron light are transferred rote the beamline 'mini-laboratories' where the chemical analysis takes place. For any given chemical question of molecular analysis, selected wavelengths of synchrotron light and a variety of synchrotron techniques are necessary to characterize different aspects of the nature and structure of molecules or materials. A few days of data collection can result in several months of data interpretation.

Beamlines can be categorized into groups or types based on selected wavelengths. These groupings include infrared, soft X-ray, and hard X-ray beamlines.

1. Electron Gun

Bursts of electons are injected into an ultrahigh vacuum stainless steel tube. The energy of the electron beam is 220 kilo-electron volts (KEY).

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2. LINAC

The linear accelerator uses microwave energy to increase the speed of the electrons to nearly the speed of light.

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3. Booster ring

The electron beam, approximately the thickness of a hair, is transferred into the booster ring where microwaves further accelerate the electrons, and increase the energy up to 2.9 giga-electron volts (GeV).

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4. Storage ring

The electron beam is then transferred into the 54-metre diameter storage ring at a current of up to 500 milli-amps Bending magnets accelerate or bend the electron beam. Insertion devices celled wigglers and undulators can bend the electron beam many times over very short distances.

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5. Synchrotron light

When high-speed, high-energy electrons are accelerated, or their path is bent in passing through powerful magnetic fields, a natural phenomenon occurs to produce an extremely brilliant, full spectrum beam of photons known as synchrotron light.

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6. Beamlines

Beams of synchrotron light are manipulated and directed onto samples to investigate the structure of molecules. At least 6 beamlines will be commissioned in 2003, with room for more than 30 beamlines in the future,

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7. Optics Hutch

The full spectrum beam of synchrotron light is segmented into portions of the electromagnetic spectrum by equipment such as monochromators, then focused with specially curved mirror systems.

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8. Experimental Hutch

The selected wavelength of synchrotron light is directed onto the sample to be analyzed. A variety of specialized detector systems can then collect very large amounts of data.

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9. Work Stations

The data is transferred to work stations for storage and analysis Scientists control the experiments and measure toe amount of light that is absorbed reflected or scattered by molecules.

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Infrared beamlines

Infrared for beamlines will capture the wavelengths of synchrotron light that are longer than visible light. IR beamlines will explore the spectral resolution of gas phase molecules, the molecular vibrations of biological molecules, and the transition states of molecules under pressure in advanced materials.

Soft X-ray beamlines

Soft X-rays include wavelengths that are shorter than visible light. Soft X-ray beamlines will be used to study the chemistry and structure of gases, liquids and solids by measuring the absorption of the light, as well as the energies and directions of various particles such as electrons emitted after a soft X-ray photon is absorbed. A variety of soft X-ray microscopes will be available to perform chemical analysis of solids and surfaces at spatial scales of 20 nanometres (1 nanometre is 1 billionth of a metre).

Hard X-ray beamlines

Hard X-rays probe matter with light of very short wavelengths, about the same size as an atom. Synchrotron techniques on hard X-ray beamlines include crystallography, scattering, spectroscopy and microanalysis. Measurements can be made of the diffraction, or bending and scattering, of the synchrotron light as it interacts with sample materials. The protein crystallography beamline will determine the structure of biological macromolecules, the function of proteins, and the molecular interactions of potential pharmaceuticals to develop improved drugs.
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Title Annotation:synchrotron light
Publication:Canadian Chemical News
Geographic Code:1CANA
Date:Jun 1, 2004
Words:825
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