The frequencies of light emitted by excited state atoms can be separated using a spectroscope. A spectroscope is an instrument that splits light into its component colors or frequencies, producing a spectrum that can be analyzed to determine the composition and properties of a substance.
There are several types of spectroscopes, but the most common one uses a prism or a diffraction grating to separate the light into its component frequencies. When light passes through the prism or grating, it is refracted or diffracted, causing the different frequencies of light to bend at different angles. This results in a separation of the light into its component colors, with each color corresponding to a specific frequency of light.
Once the light has been separated into its component frequencies, it is focused onto a detector, such as a photographic plate or a digital camera, which records the spectrum. The resulting spectrum is then analyzed to determine the emission or absorption lines of the light, which can be used to identify the elements present.
Example
When you heat a sample of sodium, it will emit light, and this light will contain a characteristic set of emission lines that are unique to sodium. When this light is passed through a prism or diffraction grating, it will be separated into its component frequencies, resulting in a series of discrete lines or "emission lines" rather than a continuous spectrum.
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The emission lines of a particular element are determined by the energy levels of its electrons and the transitions between these levels. When an electron makes a transition from a higher energy level to a lower energy level, it emits light at a specific frequency that is characteristic of the element. The resulting emission lines are unique to the element and can be used to identify it.
In contrast, when light from a continuous spectrum, such as that produced by the sun, passes through a gas cloud containing atoms of a specific element, the atoms will absorb certain frequencies of light, creating gaps or "absorption lines" in the spectrum. These absorption lines can also be used to identify the elements present in the gas cloud.
The emission spectrum was a key fact to the development of Quantum Mechanics, in particular for the Heisenberg approach to QM.
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Author of the notes: Antonio J. Pan-Collantes
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