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By recording the attenuation of light for various wavelengths, an absorption spectrum can be obtained. In physics, absorption of electromagnetic radiation is how matter (typically electrons bound in atoms) takes up a photon's energy—and so transforms electromagnetic energy into internal energy of the absorber (for example, thermal energy). [1]
Later experiments showed that these light-quanta also carry momentum and, thus, can be considered particles: The photon concept was born, leading to a deeper understanding of the electric and magnetic fields themselves. The Maxwell wave theory, however, does not account for all properties of light.
The frequencies of light that an atom can emit are dependent on states the electrons can be in. When excited, an electron moves to a higher energy level or orbital. When the electron falls back to its ground level the light is emitted. Emission spectrum of hydrogen. The above picture shows the visible light emission spectrum for hydrogen. If ...
They produce a well controlled continuous beam spanning up to 100 ms, whereas their predecessor produced only short pulses of atoms. However, this does not constitute a continuous atom laser since the replenishing of the depleted BEC lasts approximately 100 times longer than the duration of the emission itself (i.e. the duty cycle is 1/100).
To create an electron-positron pair, the total energy of the photons, in the rest frame, must be at least 2m e c 2 = 2 × 0.511 MeV = 1.022 MeV (m e is the mass of one electron and c is the speed of light in vacuum), an energy value that corresponds to soft gamma ray photons.
Therefore, two sources of light which produce the same intensity (W/m 2) of visible light do not necessarily appear equally bright. The photometry units are designed to take this into account and therefore are a better representation of how "bright" a light appears to be than raw intensity.
absorption of several photons (so called multiphoton ionization); e.g., quasi-monochromatic laser light. There are several rules that dictate the transition of an electron to an excited state, known as selection rules. First, as previously noted, the electron must absorb an amount of energy equivalent to the energy difference between the ...
Spontaneous emission is ultimately responsible for most of the light we see all around us; it is so ubiquitous that there are many names given to what is essentially the same process. If atoms (or molecules) are excited by some means other than heating, the spontaneous emission is called luminescence. For example, fireflies are luminescent.