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What does Racah mean?

What do you mean by Racah parameter?

When an atom has more than one electron there will be some electrostatic repulsion between those electrons. The total repulsion can be expressed in terms of three parameters A, B and C which are known as the Racah parameters after Giulio Racah, who first described them. ...

What is meant by Nephelauxetic effect?

The nephelauxetic effect is a term used in the inorganic chemistry of transition metals. It refers to a decrease in the Racah interelectronic repulsion parameter, given the symbol B, that occurs when a transition-metal free ion forms a complex with ligands.

What do you know about charge transfer spectra?

Charge transfer spectra in highly ionic crystals correspond to electron transfer between neighboring atoms. They can be classified as donor or acceptor, depending upon whether the metal atom donates or accepts an electron. ... The relationship of optical and chemical charge transfer processes are examined.

How do you find the racah parameter?

The ratio between the first two transitions is calculated as ν2 / ν1 which is equal to 25400 / 17400 = 1.448. In order to calculate the Racah parameter, B, the position on the horizontal axis where the ratio between the lines representing ν2 and ν1 is equal to 1.448, has to be determined.

image-What does Racah mean?
image-What does Racah mean?
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What is meant by Inter electronic repulsion?

Inter electronic repulsion as the name indicates repulsion between electrons. This take place in atoms, where electrons are present within the same shell or in different shell. This also take place when two electrons are present within the same orbital because of which hund's rule is obeyed.Feb 13, 2012

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What is the macrocyclic effect?

The macrocyclic effect is the high affinity of metal cations for macrocyclic ligands, compared to their acyclic analogues.

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What is racah parameter discuss the factor which affects its magnitude?

When an atom has more than one electron there will be some electrostatic repulsion between those electrons. The amount of repulsion varies from atom to atom, depending upon the number and spin of the electrons and the orbitals they occupy.

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What is chelate effect?

The chelate effect is the enhanced affinity of a chelating ligand for a metal ion compared to its monodentate ligand counterpart(s). This term comes from the Greek chelos, meaning "crab". ... Tridentate ligands, which bind through three donors, can bind even more tightly than bidentate, and so on.Apr 22, 2021

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What is the difference between dd transition and charge transfer?

Srividya Swaminathan d-d transitions are symmetry forbidden (Laporte selection rule), and therefore less intense. MLCT (or any charge transfer) transitions are far more intense. Typically, molar extinction coefficients for d-d transitions are in the range of 200-500 M-1 cm-1 whereas that for the MLCTs is >1000 M-1cm-1.

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How can charges be transferred?

Three ways electrons can be transferred are conduction, friction, and polarization. In each case, the total charge remains the same. This is the law of conservation of charge. Conduction occurs when there is direct contact between materials that differ in their ability to give up or accept electrons.Oct 17, 2019

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How many charge transfer spectra are found in metal complexes?

There are chiefly three types of charge transfer spectrum (a) Ligand to metal chare transfer spectrum (LMCT) (b) Metal to ligand charge transfer spectrum (MLCT) (c) Metal to metal charge transfer spectrum (MMCT) Both of these transitions will be discussed in detail in the following section.

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What are Racah's W-coefficient?

  • Racah's W-coefficients were introduced by Giulio Racah in 1942. These coefficients have a purely mathematical definition. In physics they are used in calculations involving the quantum mechanical description of angular momentum, for example in atomic theory . The coefficients appear when there are three sources of angular momentum in the problem.

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Where is the crater Racah located?

  • Racah is a lunar impact crater on the far side of the Moon. It lies almost due south of the larger crater Daedalus, and lies across lunar longitude 180°W, i.e. the longitude that is diametrically opposite to the Earth. To the west-southwest of Racah is the crater Aitken, and to the southeast lies De Vries.

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What is the difference between recoupling and Racah coefficients?

  • Recoupling coefficients are elements of a unitary transformation and their definition is given in the next section. Racah coefficients have more convenient symmetry properties than the recoupling coefficients (but less convenient than the 6- j symbols). , as explained in the article on Clebsch–Gordan coefficients.

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What are Racah's W-coefficient?What are Racah's W-coefficient?

Racah's W-coefficients were introduced by Giulio Racah in 1942. These coefficients have a purely mathematical definition. In physics they are used in calculations involving the quantum mechanical description of angular momentum, for example in atomic theory . The coefficients appear when there are three sources of angular momentum in the problem.

Related

Where is the crater Racah located?Where is the crater Racah located?

Racah is a lunar impact crater on the far side of the Moon. It lies almost due south of the larger crater Daedalus, and lies across lunar longitude 180°W, i.e. the longitude that is diametrically opposite to the Earth. To the west-southwest of Racah is the crater Aitken, and to the southeast lies De Vries.

Related

What is the difference between recoupling and Racah coefficients?What is the difference between recoupling and Racah coefficients?

Recoupling coefficients are elements of a unitary transformation and their definition is given in the next section. Racah coefficients have more convenient symmetry properties than the recoupling coefficients (but less convenient than the 6- j symbols). , as explained in the article on Clebsch–Gordan coefficients.

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