Search results
Results from the WOW.Com Content Network
Clar's rule has also been supported by experimental results about the distribution of π-electrons in polycyclic aromatic hydrocarbons, [7] valence bond calculations, [8] and nucleus-independent chemical shift studies. [9] Clar's rule is widely applied in the fields of chemistry and materials science.
The green point is a charge q lying inside the sphere at a distance p from the origin, the red point is the image of that point, having charge −qR/p, lying outside the sphere at a distance of R 2 /p from the origin. The potential produced by the two charges is zero on the surface of the sphere.
It began with the Euler beta function model of Gabriele Veneziano in 1968 for a 4-particle amplitude which has the property that it is explicitly s–t crossing symmetric, exhibits duality between the description in terms of Regge poles or of resonances, and provides a closed-form solution to non-linear finite-energy sum rules relating s- and t ...
Thomas' result convinced Pauli that electron spin was the correct interpretation of his two-valued degree of freedom, while he continued to insist that the classical rotating charge model is invalid. [34] [6] In 1927, Pauli formalized the theory of spin using the theory of quantum mechanics invented by Erwin Schrödinger and Werner Heisenberg.
The rotating-wave approximation is an approximation used in atom optics and magnetic resonance. In this approximation, terms in a Hamiltonian that oscillate rapidly are neglected. This is a valid approximation when the applied electromagnetic radiation is near resonance with an atomic transition, and the intensity is low. [ 1 ]
Arrow pushing or electron pushing is a technique used to describe the progression of organic chemistry reaction mechanisms. [1] It was first developed by Sir Robert Robinson.In using arrow pushing, "curved arrows" or "curly arrows" are drawn on the structural formulae of reactants in a chemical equation to show the reaction mechanism.
If this (on-resonance) pulse is shone on a collection of atoms originally all in their ground state (w = −1) for a time = /, then after the pulse, the atoms will now all be in their excited state (w = +1) because of the (or 180°) rotation about the u axis.
The first step involves a photochemically induced conrotatory ring opening of 7-dehydrocholesterol to form pre vitamin D3. A [1,7]-hydride shift then forms vitamin D 3 . Another example is in the proposed biosynthesis of aranotin, a naturally occurring oxepine, and its related compounds.