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Light - Brightening the World of Chemistry (Part Two)

Light - Brightening the World of Chemistry (Part Two)

Date Published: 22-Apr-15

In part one of ‘Light – Brightening the World of Chemistry’ we explained what light is and shared how our scientists use light to determine the concentration of solutions using colourimetry. 

In part two, we take a closer look at another analytical technique seen in the ChemCentre lab; Atomic Emission Spectrometry (AES) and explore the connection to brightly coloured fireworks.

What is Atomic Emission Spectrometry and how does it work?

AES works by analysing the wavelength of light emitted by an atom. This light is given out after an atom has been excited by an energy source. At ChemCentre we spray the sample through an argon plasma flame that is approximately 9500°C. Once the atom has been excited, it needs to lose that energy; it does this by giving off light. The wavelength of light that the atom gives off is specific to each element, and the number of wavelengths of light that can be detected per element can be upwards of twenty! Depending on what wavelength of light is selected by our chemists and how much is emitted we can calculate how much of a particular atom is in a sample.

This instrument is particularly well suited for metals as it is capable of scanning the entire UV and visible spectrums for emissions in a matter of seconds, allowing us to acquire data about a large range of important environmental chemicals at one time.

Where do we see this science in everyday life?

The science behind fireworks is based on the same principle as AES. The different colours within fireworks are produced by heating different metals that release energy as coloured light as they cool. You can see this in action in the image below where strontium ions give off red light when sprayed through a Bunsen burner at our Open Day last year.

strontium ions through flame


Want a little more science?

When an atom becomes excited one of the electrons jumps up to a higher energy level. It is this discrete energy difference between energy levels that dictates what wavelength light will be emitted. Our Atomic Emission Spectrometers can detect light of wavelengths differing by only 0.001nm.

If you would like any more information on any of the topics covered in our International Year of Light articles contact us at newsletter@chemcentre.wa.gov.au or via Twitter and Facebook.

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