Quadrupole magnetically induced

Further experimental examples of temperature-dependent and magnetically-induced quadrupole splittings are provided in the first volume of this book (Chap. 6, see CD-ROM, Part VI) and also in Sect. 9.4 in Chap. 9 of the present volume. 

The quantity on the left is the Fourier component of the dipole moment induced by the optical field Max(w). These equations can be generalized to mixed frequency-dependent electric dipole, electric quadrupole, magnetic dipole properties, and similar equations can be written for the Fourier components of the permanent electric quadrupole, aj8(magnetic dipole, ma(co). For static Maxwell fields similar expansions yield effective (starred) properties, defined as derivatives of the electrostatic free energies. 

Evidence for magnetically induced nuclear quadrupole interaction Further evidence for non-s, especially orbital contributions to the hyperfine interaction in magnetically ordered intermetallic compounds is obtained from a closer inspection of nuclear quadrupole interactions. For an electric field gradient (EFG) of axial symmetry eq = caused, e.g., by the low-symmetry arrangement of ionic charges in the crystal lattice, the quadrupole interaction of the nuclear spin / with the quadrupole moment eQ (Barnes 1979, McCausland and Mackenzie... 

The magnetically induced electric quadrupolar interaction was recently observed in several cubic, ferromagnetically ordered intermetallic compounds at the nucleus of the rare-earth S-state ions Gd and Eu, despite the fact that the nuclei are residing on nominally cubic lattice sites e.g., nuclear quadrupole... 

It is well known that a Mossbauer-active nucleus senses its local environment via direct and indirect exchange mechanisms (see Fig. 18.28) [I 1,94]. Direct interactions include (i) interaction between atomic shell and nucleus of a Mossbauer-active atom (interaction of Type I), (ii) interaction between the nucleus of the Mossbauer-active atom and its surrounding lattice (interaction of Type III), and (Mi) interaction between Bext nd nucleus of the Mossbauer-active atom (interaction of Type V). On the other hand, indirect interactions involve (i) interaction between the lattice and atomic shell of the respective nucleus of the Mossbauer-active atom (interaction of Type II) and (ii) interaction between Bgxt and atomic shell of the respective nucleus of the Mossbauer-active atom (interaction of Type IV). Thus, Bgxt can act directly or indirectly on the nucleus of the Mossbauer-active atom and affects its nuclear levels. Beside this, Bgxt can magnetically induce a quadrupole interaction that frequently happens, for example, in the case of Fe " " having a cubic environment. Interaction of Type IV and Type V can be effectively described by Hamiltonians in the form of [94]... 

GdAlj A1 4.2K T 0.64r. observed transferred magnetically induced A1 quadrupole interaction Degani and Kaplan (1973)... 

Laser ablation ICP-MS is used for direct analysis of the elemental and isotopic composition of solid samples. Photons from the laser system are focused into a high peak power energy pulse that interacts with the sample. As a result of this interaction, small particles, atoms and ions are removed from the topmost atomic layers forming a laser-induced aerosol above the sample surface. The aerosol is then transported by an inert gas stream to the ICP-MS. After vaporization, atomization and ionization of the particles in the ICP, quadrupole, magnetic sector field or time-of-flight mass filters are used for mass separation. Because of the properties of the laser systems available today, bulk analysis with low spatial resolution (>100 p-m) as well as local analysis with high spatial resolution (<20 p.m) are possible. Since only small sample amounts are ablated per laser shot, a high sensitivity analytical detection system is a prerequisite for trace and ultratrace analysis. 

Tandem quadrupole and magnetic-sector mass spectrometers as well as FT-ICR and ion trap instruments have been employed in MS/MS experiments involving precursor/product/neutral relationships. Fragmentation can be the result of a metastable decomposition or collision-induced dissociation (CID). The purpose of this type of instrumentation is to identify, qualitatively or quantitatively, specific compounds contained in complex mixtures. This method provides high sensitivity and high specificity. The instrumentation commonly applied in GC/MS is discussed under the MS/MS Instrumentation heading, which appears earlier in this chapter. 

The perturbation of the four substates of the excited 7 = 3/2 manifold by induces a typical asymmetry of the resulting magnetically split Mossbauer spectrum as pictured at the bottom of Fig. 4.10 for positive the inner four lines, 2-5, are shifted to lower velocities, whereas the outer two lines, 1 and 6, are shifted to higher velocities by equal amounts. In first order, the line intensities are not affected. For negative the line asymmetry is just inverted, as the quadmpole shift of the nuclear 1/2 and 3/2 states is opposite. Thus, the sign and the size of the EFG component along the field can be easily derived from a magnetic Mossbauer spectrum with first-order quadrupole perturbation. 

Quadrupole splitting (A q) correlates to electric field gradient and, based on model compounds, can identify some ligand types Can observe changes in ligand field induced by sample perturbation Can only detect iron sites Magnetic circular dichroism (MCD) spectra Require low temperature to observe (—2-70 K)... 

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