This means that line spectra can be used to identify elements.Ĭontinuous spectra are produced by electrons being shared between many atoms, giving a huge range of possible frequencies, as shown below. As a result each produces photons with different energy and so the line spectra for different elements will be different. This is not a continuous spectrum as only light of specific frequencies and specific colours are produced.ĭifferent types of atoms have different energy levels. When the atom is excited with a defined energy, an emission spectrum is observed with. This causes line emission spectra to be produced, as shown below. individual levels take place according to defined selection criteria. This means that each electron transition will produce a photon of a different frequency and hence a different colour. Similar to the human eyes brightness and chromatic adaptation, such normalization by a down-welling flux helps the interpretability. The absorbed light is isotropically re-emitted at a random wavelength distributed according to the emission spectrum of the quantum dot. \(f\) is the frequency of light producedĪs the energy levels have different values, each of the possible electron transitions within an atom will produce a photon with a different energy. Spectral reflectance is the ratio of upwelling to down-welling radiant fluxes for given surface, illumination and observation properties, including the sensors spectral sampling properties.If an electron moves from level \(E_\) the energy of the photon can be worked out using the following: If this cloud can be excited by a nearby source of energy such as hot, young stars or an active galactic nucleus then the electrons in atoms of the gas cloud can get excited. The energy of the photon can be worked out using the equation Emission spectrum: A third possibility occurs if an observer is not looking directly at a hot black body source but instead at a diffuse cloud of gas that is not a black body. ![]() The amount of energy it loses will be equal to the difference in the energy levels it moves between. As energy is linked to wavelength (or color), this results in the optical properties of the particle being tunable based on its size. If an electron is in an excited state it can return to a lower energy level.
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