Hanle effect linear

Fig. 4.11. Hanle effect on the degree of linear polarization V = (/y — Iff/(I + Iff) at (P, f )-excitation 1 - superpositional signal calculated at the same conditions as Fig. 4.10, dots refer to the positions a, b, c, d as in Fig. 4.10 2 - pure excited state signal at x = 0 3 - pure ground state signal at gj> = 0 4 - experimentally measured dependence for Te2 under conditions as given in Fig. 4.6, curve 1, but in the region of weaker magnetic field and at strong pumping (x 3).

Note that the superpositional Hanle signal, reflecting overlapping of effects from both levels, coupled with optical excitation, is sensitive to the signs of the Lande factors gj> and gj even with Lorentzian geometry, where

difference between the cases... 

Linear approximation excited state Hanle effect... 

The result obtained reflects linear approximation, i.e. manifestation of the usual linear (observable signal is proportional to Tp) Hanle effect (Section 4.2). This contention becomes obvious if we substitute the polarization moments obtained into the expression for fluorescence intensity (5.34) and find the form of the degree of polarization V = (Iy — Ix)/(Iy + Ix) (Fig. 5.8). For instance, for a radiative transition (J = 1) -> (J" = 1), and using Table C.3 for numerical values of 6j-symbols and for values of from Table 2.1, we obtain... 

This leads to the manifestation of the non-linear Hanle effect in the ground state (the observed signal is proportional to T2). The non-linearity of the effect is not obvious in this case and consists of the following fact. Despite the fact that the approximation (5.63), (5.64), (5.65) and (5.66) is linear with respect to the light field (proportional to Tp), it is necessary for observation of the Hanle signal (5.61) to calculate the second (2) (i)... 

Probably coherent effects in atomic excitation with light were studied first by Wilhelm Hanlc. The very first publication about the effect, which is now called Hanle effect, appeared in Zeitschrift fur Physik as early as in 1924 [1]. In the paper it was shown that the resonance fluorescence of Hg excited with linear polarized light is depolarized by an external magnetic field. That publication docs... 

By using circularly and linearly polarized light alternatively in the same geometry, Omont (1965a) was able to measure both Pg and Pg using the Hanle effect in iso-198... 

It is rather likely that understanding of the anisotropic distribution of the angular momenta of atoms was enhanced by Hanle s [184] discovery in 1924. Hanle observed the effect of the disappearance of linear polarization in fluorescence in a weak magnetic field directed at right angles to the E-... 

If we assume the lower level Lande factor as known, then the fit of non-linear Hanle signals permits us to determine the relaxation constants 7K = 7, as well as the effective cross-sections light field, which mixes the multipole moments aPq with different k, does not permit us to determine the values for definite k separately. Nevertheless (Section 3.3), the discrepancies between the 7K values are negligible in many cases, and the information obtained is sufficiently reliable. 

The measurement of ultraweak magnetic fields is one more area of effective application of optically oriented atoms. Its source lies in an effect studied by Hanle as far back as 1925 in experiments on the fluorescence of Hg vapor in the presence of a magnetic field. When Hg vapor is irradiated with linearly polarized light in resonance... 

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