Photonics Dictionary: R

A statistical analysis of facts obtained when the intensity of x-ray diffraction is calculated at different angles. In this way, the interatomic distances of gases and liquids can be deduced, with...

That process by which radiation spontaneously emitted by a volume of optical materials is resonantly reabsorbed within the same volume before it escapes. This effect is manifested in a reduction in...

The fundamental wavelength standard of time or frequency. An atomic standard, it is properly expressed as 9,192,631,770 times the frequency of the transition between the hyperfine structure levels of...

In atomic fluorescence spectroscopy, fluorescence emitted by an atom at a spectral line of a wavelength identical to that of the stimulating radiation.

A type of ultrasensitive laser spectroscopy that can detect quantities as small as a single atom of some substances and that can differentiate between isobars of different elements.

That radiation emitted by an atom or molecule that has the same frequency as that of an incident particle; e.g., a photon. It generally involves a transition to the lowest energy level of the atom or...

One of the types of change in the energy levels of molecules or atoms in a laser that can result in lasing action. Because the energy levels between rotational states are small, such lasing action is...

The term "Rydberg atom" refers to an atom in a highly excited state where one or more of its electrons are in a Rydberg orbital. A Rydberg atom is characterized by having an electron orbit that is...