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Rovibronic Excitation
Rovibronic coupling denotes the simultaneous interactions between rotational, vibrational, and electronic degrees of freedom in a molecule. When a rovibronic transition occurs, the rotational, vibrational, and electronic states change simultaneously, unlike in rotational–vibrational coupling, rovibrational coupling. The coupling can be observed spectroscopically and is most easily seen in the Renner–Teller effect in which a linear polyatomic molecule is in a degenerate electronic state and bending vibrations will cause a large rovibronic coupling. See also * Afterglow plasma * Vibronic coupling Rotation Molecular vibration {{chemistry-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotational–vibrational Coupling
In physics, rotational–vibrational coupling occurs when the Angular frequency, rotation frequency of a Physical system, system is close to or identical to a Natural frequency, natural internal vibration frequency. The animation on the right shows ideal motion, with the force exerted by the Spring (device), spring and the distance from the Rotation around a fixed axis, center of rotation increasing together linearly with no friction. In rotational-vibrational coupling, angular velocity oscillates. By pulling the circling masses closer together, the spring transfers its stored strain energy into the kinetic energy of the circling masses, increasing their angular velocity. The spring cannot bring the circling masses together, since the spring's pull weakens as the circling masses approach. At some point, the increasing angular velocity of the circling masses overcomes the pull of the spring, causing the circling masses to increasingly distance themselves. This increasingly strains ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Renner–Teller Effect
The Renner–Teller effect is observed in the spectra of molecules having electronic states that allow vibration through a linear configuration. For such molecules electronic states that are doubly degenerate at linearity (Π, Δ, ..., etc.) will split into two close-lying nondegenerate states for non-linear configurations. As part of the Renner-Teller effect, the rovibronic levels of such a pair of states will be strongly Coriolis coupled by the rotational kinetic energy operator causing a breakdown of the Born-Oppenheimer approximation. This is to be contrasted with the Jahn-Teller effect which occurs for polyatomic molecules in electronic states that allow vibration through a symmetric nonlinear configuration, where the electronic state is degenerate, and which further involves a breakdown of the Born-Oppenheimer approximation but here caused by the vibrational kinetic energy operator. In its original formulation, the Renner–Teller effect was discussed for a triatomic molec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Afterglow Plasma
A plasma afterglow (also afterglow) is the radiation emitted from a plasma after the source of ionization is removed. The external electromagnetic fields that sustained the plasma glow are absent or insufficient to maintain the discharge in the afterglow. A plasma afterglow can either be a temporal, due to an interrupted (pulsed) plasma source, or spatial, due to a distant plasma source. In the afterglow, plasma-generated species de-excite and participate in secondary chemical reactions that tend to form stable species. Depending on the gas composition, super-elastic collisions may continue to sustain the plasma in the afterglow for a while by releasing the energy stored in rovibronic degrees of freedom of the atoms and molecules of the plasma. Especially in molecular gases, the plasma chemistry in the afterglow is significantly different from the plasma glow. The afterglow of a plasma is still a plasma and as thus retains most of the properties of a plasma. History The first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vibronic Coupling
Vibronic coupling (also called nonadiabatic coupling or derivative coupling) in a molecule involves the interaction between electronic and nuclear vibrational motion. The term "vibronic" originates from the combination of the terms "vibrational" and "electronic", denoting the idea that in a molecule, vibrational and electronic interactions are interrelated and influence each other. The magnitude of vibronic coupling reflects the degree of such interrelation. In theoretical chemistry, the vibronic coupling is neglected within the Born–Oppenheimer approximation. Vibronic couplings are crucial to the understanding of nonadiabatic processes, especially near points of conical intersections. The direct calculation of vibronic couplings is not common due to difficulties associated with its evaluation. Definition Vibronic coupling describes the mixing of different electronic states as a result of small vibrations. : \mathbf_\equiv\langle\,\chi_(\mathbf;\mathbf)\,, \, \hat_\ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotation
Rotation, or spin, is the circular movement of an object around a '' central axis''. A two-dimensional rotating object has only one possible central axis and can rotate in either a clockwise or counterclockwise direction. A three-dimensional object has an infinite number of possible central axes and rotational directions. If the rotation axis passes internally through the body's own center of mass, then the body is said to be ''autorotating'' or '' spinning'', and the surface intersection of the axis can be called a ''pole''. A rotation around a completely external axis, e.g. the planet Earth around the Sun, is called ''revolving'' or ''orbiting'', typically when it is produced by gravity, and the ends of the rotation axis can be called the ''orbital poles''. Mathematics Mathematically, a rotation is a rigid body movement which, unlike a translation, keeps a point fixed. This definition applies to rotations within both two and three dimensions (in a plane and in space, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
