in the process called Fluorescence, some substances absorb photons of one kind of radiation, and give out photons of a different kind. When infrared radiation falls on these materials, visable light is not emitted. Why not?
is it to do with the degree of which the photon increases the fluorescence energy level?
The energy given out has to be less or equal to what was received. long wave light energy of less energy than infrared cannot be seen because it is below the energy spectrum our eyes are sensitive too.
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In the process of fluorescence, certain substances absorb photons of one kind of radiation (in this case, infrared radiation) and then emit photons of a different kind (visable light).
To understand why visible light is not emitted when infrared radiation falls on these materials, we need to consider the energy of the photons involved. When a material absorbs a photon, it excites the electrons within the substance to higher energy levels. These excited electrons then release the absorbed energy by emitting photons of lower energy.
In the case of fluorescence, the emitted photons of visible light have lower energy compared to the absorbed infrared photons. This is because the energy given out during the process of fluorescence has to be less than or equal to the energy received from the incident radiation. The energy of a photon is directly proportional to its frequency (or inversely proportional to its wavelength). So, the emitted photons of visible light have a higher frequency (shorter wavelength) than infrared radiation.
The reason why we cannot see long wave light with less energy than infrared is because it falls below the energy spectrum that our eyes are sensitive to. Our eyes are most sensitive to the range of visible light, which includes wavelengths between approximately 400 to 700 nanometers. Any radiation with lower energy, such as long wave light or infrared, would not be detected by our eyes.
Therefore, the lack of visible light emission when infrared radiation falls on materials undergoing fluorescence is due to the principle of conservation of energy and the specific sensitivity of our eyes to the energy spectrum of visible light.