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The +M effect, also known as the positive mesomeric effect, occurs when the substituent is an electron donating group. The group must have one of two things: a lone pair of electrons, or a negative charge. In the +M effect, the pi electrons are transferred from the group towards the conjugate system, increasing the density of the system.
The Mössbauer effect occurs because there is a finite probability of a decay involving no phonons. Thus in a fraction of the nuclear events (the recoil-free fraction, given by the Lamb–Mössbauer factor), the entire crystal acts as the recoiling body, and these events are essentially recoil-free. In these cases, since the recoil energy is ...
Helmholtz resonance, also known as wind throb, refers to the phenomenon of air resonance in a cavity, an effect named after the German physicist Hermann von Helmholtz. [1] This type of resonance occurs when air is forced in and out of a cavity (the resonance chamber ), causing the air inside to vibrate at a specific natural frequency .
The Mössbauer effect is the resonant and recoil-free emission and absorption of gamma ray photons by atoms bound in a solid form. Resonance in particle physics appears in similar circumstances to classical physics at the level of quantum mechanics and quantum field theory .
In experiment, the incident beam that produces resonance always has some spread of energy around a central value. Usually, that is a Gaussian/normal distribution.The resulting resonance shape in this case is given by the convolution of the Breit–Wigner and the Gaussian distribution,
The damping force ensures that the oscillator's response is finite at its resonance frequency. For a time-harmonic driving force which originates from the electric field, Newton's second law can be applied to the electron to obtain the motion of the electron and expressions for the dipole moment , polarization , susceptibility , and dielectric ...
The multipactor effect is a phenomenon in radio-frequency (RF) amplifier vacuum tubes and waveguides, where, under certain conditions, secondary electron emission in resonance with an alternating electromagnetic field leads to exponential electron multiplication, possibly damaging and even destroying the RF device.
The resonance frequencies of the system depend on the properties of all components and their couplings, and are independent of which is driven. The antiresonances, on the other hand, are dependent upon everything except the component being driven, therefore providing information about how it affects the total system.