Zeeman effect 7-value

Not only can electronic wavefiinctions tell us about the average values of all the physical properties for any particular state (i.e. above), but they also allow us to tell us how a specific perturbation (e.g. an electric field in the Stark effect, a magnetic field in the Zeeman effect and light s electromagnetic fields in spectroscopy) can alter the specific state of interest. For example, the perturbation arising from the electric field of a photon interacting with the electrons in a molecule is given within die so-called electric dipole approximation [12] by ... 

In the previous section it has been shown that the measured sample absorbance may be higher than the true absorbance signal of the analyte to be determined. This elevated absorbance value can occur by molecular absorption or by light scattering. There are three techniques that can be used for background correction the deuterium arc the Zeeman effect and the Smith-Hieftje system. 

Microwave spectra obtained from PHgD and PHDa in a magnetic field of about 25 kG showed Zeeman effects, from which molecular g values were calculated. They were 20 times smaller than those for ammonia. The molecular quadrupole moments of phosphine and ammonia were approximately the same. Magnetic susceptibilities and molecular quadrupole moments were also compared. 

In the presence of magnetic field a further splitting into (2J+l) equispaced energy levels occurs. These correspond to the number of values that can be assumed by the magnetic quantum number M ranging from +J>M>—J (Zeeman effect). 

The influence of a magnetic field on gaseous atoms induces a splitting of each line into several polarised components. This phenomenon, which can be seen in the emission or absorption spectra of these atoms and is called the Zeeman effect, arises from perturbations in the energy states of electrons in the atom (Fig. 14.13). For example, the absorption wavelength of cadmium, situated at 228.8 nm, leads to three polarised absorption bands due to the Zeeman effect. One of these bands, the it component, retains the initial value of the wavelength whereas the other two, the a components, are symmetrically shifted by a few picometres relative to the 7r component in a 1-tesla field. The direction of polarisation of the 7r and a lines are perpendicular and the polarisation plane of the 7r component is parallel to the magnetic field (Fig. 14.14). 

Note that if L = 0 in equation (67) then J = S and g = 2, the spin-only-value . The energy pattern of Figure 27 is linear in H there is no second-order Zeeman effect unless other states are considered. Application of equation (64) to this system is fairly straightforward since it yields... 

Transitions between the two spin states (+1/2 and -1/2) can be induced by oscillating electromagnetic radiation (v in the microwave region) applied perpendicularly to 77. The energy-level splitting is referred to as the Zeeman effect, illustrated in Figure 16.1. Normally in the EPR measurements, v is maintained at a fixed value and 77 is permitted to vary until the resonance is matched. 

Figure 16.1. (a) Simplified scheme of EPR phenomenon, showing the energy-level splitting (Zeeman effect) for the electron spin S = 1/2 (Ms = +1/2) as a function of applied magnetic field (H), (b) the EPR absorption line, and (c) first derivative of absorption line, indicating the g value and line width (AH), normally detected in the EPR spectra. 

Flygare, W.H. and Benson, R.C. (1971). The molecular Zeeman effect in diamagnetic molecules and the determination of molecular magnetic moments (g values), magnetic susceptabilities, and molecular quadrupole moments, Mol. Phys., 20, 225-250. 

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