Stimulated transitions

Note that we have drawn CP approaching zero as 0. This feature is a general phenomenon, and explained by quantum mechanics. At low temperatures, the energy available is so small that there is not enough to stimulate transitions to higher energy states, so the sample cannot take up energy, and its capacity for heat is zero. 

Taber, K. S. (2005). Learning quanta Barriers to stimulating transitions in student understanding of orbital ideas. Science Education, S9(l), 94-116. 

Maser The microwave equivalence of a laser. A stimulated transition in a molecule that relaxes a population inversion in an excited state... 

The key prerequisite for optical amplification via stimulated emission is that the emitted photons propagate through the gain medium long enough to initiate further stimulated transitions. This condition can be expressed as... 

Soon after the first successful experimental verification of an optical maser the search for possible new laser media began and, especially in the infrared region, numerous stimulated transitions were discovered many of them had not even been observed previously in spontaneous emission... 

Both of these analyses rely on the fact that, to produce stable antihydrogen, the relaxation processes must occur before the atom leaves the plasma, otherwise it will be field ionized. Alternatively, as discussed by Wolf (1993), it may be possible to laser-stimulate transitions to more tightly bound levels to avoid the field-ionization problem. 

The finite temperature effect can be described as usual one should take into account the stimulated transitions. As a result, one gets an additional factor (1 — exp( -n rymU... 

The third term describes the stimulated transitions, the fourth term describes the relaxation of the polarization moments of corresponding rank, together with the effect of the external field. 

The principle of the experiment is to see an increase in the intensity due to laser-stimulated transitions when negative muons are stopped in the helium gas present in a multipass optical cavity, where a high-density electromagnetic radiation of the correct wavelength is stored it is crucial here that the lifetimes of the levels in which one is interested are around 10 12 s (we recall that the negative muon cascade time is about 1 ns or less). 

Figure 6.26. Population cases in a two-level system and the consequences of stimulated transitions.

Figure 10.27. Spontaneous and stimulated transitions in a simple two-level system.

Due to the extremely low density of phonons at the Larmor frequency the probability of causing a directly stimulated transition is almost negligible. 

The stimulated transitions between the four energy levels of two coupled spins result in two distinct types of relaxation. The first is called spin-lattice relaxation. This form of relaxation involves the net loss of energy from the excited state and is analogous... 

The absorption of energy stimulating transitions between the two levels of energy in a magnetic field is called magnetic resonance. Thus, the resonance condition obtained by equaling Eo to AE can be expressed either as ... 

The selection rules of the new quantum theory allow electric dipole transitions between levels of the same n, but since the probability of spontaneous transition depends on the cube of the frequency, such transitions in hydrogen are exceedingly improbable. Stimulated transitions, on the other hand, may take place under quite small alternating electric fields of the appropriate frequency. Absorption and emission of energy by the atom are equally probable, so that a change in an assembly of atoms may only be detected if the two states between which transitions are taking place are unequally populated at the outset. 

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