Application of Diffraction Gratings
Applied Science: BTEC Level 3 National Extended Diploma, topic 1.6.10
Applications of Diffraction Gratings
Diffraction gratings are very useful for physicists.
Analysing light
- Diffraction gratings can be used to separate wavelengths in light from different substances, producing emission spectra.
- The wavelengths present can help us learn new things about the substance being tested.
Atomic spacing in crystals
- Atoms in a crystal can act like a diffraction grating, with little gaps for light to pass through.
- We can find the spacing between the atoms in the crystal by looking at how X-rays diffract through the crystal.
Emission Spectra
Electrons in atoms can only move between discrete energy levels. So an atom can only absorb or emit photons with particular frequencies (or wavelengths).
Excited gas
- An excited gas contains atoms in excited energy states.
- These excited atoms contain electrons in high energy levels.
- As these electrons de-excite and fall back to lower energy levels, photons are emitted.
Photon emission
- These photons carry away energy from the atoms.
- The amount of energy (and so what frequency) the photons have depends on the difference in energy levels in the atom.
- For every possible electron transition, there will be a unique frequency photon emitted.
- We see a series of bright lines when we pass the emitted light through a prism or diffraction grating.
Identify gases
- Emission spectra are unique to each type of atom.
- We can use emission spectra to identify gases in a sample by comparing its emission spectra to those of known elements and compounds.
Test yourself on Application of Diffraction Gratings
Which of these roles can a diffraction grating perform?
When an electron falls to a lower energy level what happens?
Which of these is true about emission spectra?