Fine structure, in spectroscopy, the splitting of the main spectral lines of an atom into two or more components , each representing a slightly different wavelength. Fine structure is produced when an atom emits light in making the transition from one energy state to another.
Why is fine structure important?
The fine structure constant, α, also plays a major role in one of the most important experiments going on in modern physics today: the effort to measure the intrinsic magnetic moment of fundamental particles . ... and a constant, known as g, which is a purely quantum mechanical effect.
Who introduced the fine structure of an atom?
As a dimensionless quantity, its numerical value, approximately 1137, is independent of the system of units used. While there are multiple physical interpretations for α, it received its name from Arnold Sommerfeld , who introduced it in 1916, when extending the Bohr model of the atom.
What is fine structure and hyperfine structure?
Fine structure describes the splitting of the spectral lines of atoms due to electron spin and relativistic corrections to the non-relativistic Schrödinger equation. ... The hyperfine structure is caused by interaction between magnetic field (from electron movement) and nuclear spin.
What is the fine structure of hydrogen atom?
When the familiar red spectral line of the hydrogen spectrum is examined at very high resolution, it is found to be a closely-spaced doublet . This splitting is called fine structure and was one of the first experimental evidences for electron spin.
Why is it called the fine structure?
The split lines, which are called the fine structure of the main lines, arise from the interaction of the orbital motion of an electron with the quantum mechanical “spin” of that electron . ...
Who discovered fine structure constant?
Introduction. Arnold Sommerfeld introduced the fine structure constant into physics in the 1920s in order to account for the splitting of atomic spectral lines.
What is temporal fine structure and why is it important?
Using speech chimeras, the authors revealed that TFS is important for pitch perception and sound localization . Other way to study the role of TFS is to remove ENV cues in the speech as far as possible while TFS cues are preserved.
How is the fine structure constant calculated?
atomic spectra
...a dimensionless constant called the fine-structure constant. This constant is given by the equation α = ke 2 /hc , where k is Coulomb’s constant, e is the charge of the electron, h is Planck’s constant, and c is the speed of light.
Is the fine structure constant changing?
The fine structure constant has not changed in time . ... Earlier results have shown that the fine structure is slightly different along a specific axis of the Universe, called a dipole. Now, the latest result is from a single light source along a specific direction, so it’s not definitive on its own.
What is the origin of hyperfine structure?
In atoms, hyperfine structure arises from the energy of the nuclear magnetic dipole moment interacting with the magnetic field generated by the electrons and the energy of the nuclear electric quadrupole moment in the electric field gradient due to the distribution of charge within the atom.
What is doublet line structure?
The term “doublet” dates back to the 19th century, when it was observed that certain spectral lines of an ionized, excited gas would split into two under the influence of a strong magnetic field , in an effect known as the anomalous Zeeman effect.
What are hyperfine lines?
Hyperfine structure (HFS), in spectroscopy, the splitting of a spectral line into a number of components . The splitting is caused by nuclear effects and cannot be observed in an ordinary spectroscope without the aid of an optical device called an interferometer.
What is Lambda shift?
In physics, the Lamb shift, named after Willis Lamb, is a difference in energy between two energy levels 2 S 1 / 2 and 2 P 1 / 2 (in term symbol notation) of the hydrogen atom which was not predicted by the Dirac equation, according to which these states should have the same energy.
How is degeneracy calculated?
So the degeneracy of the energy levels of the hydrogen atom is n 2 . For example, the ground state, n = 1, has degeneracy = n 2 = 1 (which makes sense because l, and therefore m, can only equal zero for this state).
What is atomic structure?
Atoms consist of three basic particles: protons, electrons, and neutrons . The nucleus (center) of the atom contains the protons (positively charged) and the neutrons (no charge). The outermost regions of the atom are called electron shells and contain the electrons (negatively charged).
