Zeeman region

In the Zeeman region for the fine structure, in which Mj is well-defined, we can write... 

The plus sign corresponds to the sublevels originating in the tiigher J level. In Fig. 2.12 the magnetic field behaviour of a P state with a fine-structure splitting of 110 cm is shown. In the Zeeman region E- -C 110cni )... 

In [49, 76], the line intensities for electric quadrupole and Zeeman (magnetic dipole) splitting and including the anisotropy of the /-factor are also given for / = 2 <-> 7g = 0 transitions (even-even isotopes, e.g., in the rare earth region or in W, Os). 

For routine studies with the ESR spectrometer, it is most convenient to work at X-band frequencies ( 9.5 MHz or 3 cm). The sample is usually contained in a 4 or 5 mm diameter quartz tube having a sensitive region about 2 cm in length. An alternative frequency is at Q-band ( 35,000 MHz or 1 cm). Here, the cavity dimensions are much smaller and the diameter of the sample tube is less than 2 mm. This creates some problems in handling and degassing powder samples. By varying the frequency it is possible to determine which features in a spectrum are due to Zeeman interactions... 

Instead of tuning the laser line, one can also shift the absorption lines across the laser line by Zeeman or Stark effects. This is especially advantageous in the far-infrared region where the tuning range of laser lines is restricted. 

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. 

A collinear magnetic field is used to Zeeman shift the transition out of resonance until the atom reaches the detection region. 

Although the resonance Is shifted by Zeeman- and motional Stark-effects due to a residual magnetic field of about 75 G in the transition region, the results are promising and lead to the expectation of improved precision in future excited state experiments. 

Figure 9.25. Zeeman splitting of the N = 1 and 2 rotational levels in the CN radical. In region 1 the rotational transition is electric dipole allowed and magnetically tunable. In region 3 the magnetically-tunable transitions are magnetic dipole electron spin transitions the electric dipole transitions are not magnetically tunable. Region 2 is intermediate between these limiting cases.

Figure 11.24. Experimental arrangement used by Ernst and Kindt [44] in their pump/probe microwave/optical double resonance study of a rotational transition (18.2 GHz) in the ground state of CaCl. The photomultiplier tubes which monitor fluorescence are situated on the axis perpendicular to both the laser beam and the molecular beam. The C region, where the molecular beam is exposed to microwave radiation, is magnetically shielded to minimise stray Zeeman effects. The microwave power was amplitude modulated at 160 Hz and the modulated fluorescence detected by photomultiplier B. 

The third field region observed in the MARY curve shows a reversion of the field effect relative to the Zeeman effect saturation. We saw previously that the rate of S-Tq mixing depends on the difference in Larmor precession frequencies of the two radicals and that this difference may arise from a difference in the g-values of the radicals. This frequency difference is proportional to the strength of the applied field. As the g-value... 

Fig. 4. Excitation spectra of Pd(2-thpy)2 in n-octane (a) at T = 1.3 K and (b) to (e) at T=1.5 K, respectively. Concentration c = 10 mol 1 The emission is detected at v j t = 17,702 cm (18,418 cm - 716 cm vibrational satellite). The excitation spectra (b) to (e) show the region of the electronic origin near 18,418 cm on an enlarged scale. With application of high magnetic fields up to B = 12 T,the origin line at 18,418 cm (0-0 transition) splits into three Zeeman lines. (Compare Refs. [56,74])...

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