Search results
Results from the WOW.Com Content Network
Clar's rule states that for a benzenoid polycyclic aromatic hydrocarbon (i.e. one with only hexagonal rings), the resonance structure with the largest number of disjoint aromatic π-sextets is the most important to characterize its chemical and physical properties.
Erich Clar (23 August 1902 – 27 March 1987) was an Austrian organic chemist, born in Hřensko, who studied polycyclic aromatic hydrocarbon chemistry. He is considered as the father of that field. [ 1 ]
The principal U(1)-connection ∇ on the line bundle has a curvature F = ∇ 2, which is a two-form that automatically satisfies dF = 0 and can be interpreted as a field strength. If the line bundle is trivial with flat reference connection d we can write ∇ = d + A and F = d A with A the 1-form composed of the electric potential and the ...
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 ]
Scheme of a quadrupole ion trap of classical setup with a particle of positive charge (dark red), surrounded by a cloud of similarly charged particles (light red). The electric field E (blue) is generated by a quadrupole of endcaps (a, positive) and a ring electrode (b). Picture 1 and 2 show two states during an AC cycle.
An observer at rest with respect to a system of static, free charges will see no magnetic field. However, a moving observer looking at the same set of charges does perceive a current, and thus a magnetic field. That is, the magnetic field is simply the electric field, as seen in a moving coordinate system.
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.
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.