Chapter 5 Multiple Choice Questions

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. Calculate the anisotropic g values for the axial paramagnetic centre shown in Fig. 5.9c.

= 2.35; = 2.020 correct incorrect

= 2.25; = 2.200 correct incorrect

= 2.15; = 2.040 correct incorrect

= 2.05; = 2.002 correct incorrect

= 2.50; = 2.009 correct incorrect

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. For the 2 x 2 matrix M = , find the inverse M^-1 in terms of a.

M^-1 = correct incorrect

M^-1 = correct incorrect

M^-1 = correct incorrect

M^-1 = correct incorrect

M^-1 = correct incorrect

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. Calculate the product of the following row, square matrix and column vector:

-14 correct incorrect

-27 correct incorrect

156 correct incorrect

48 correct incorrect

-128 correct incorrect

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. A surface paramagnetic defect in photo-irradiated TiO₂ produces an axial g tensor with the values = 2.005 and = 2.002. Calculate the B_res value for an applied magnetic field angle of θ = 25° with respect to the unique z axis (ν = 9.5 GHz).

338.61 mT correct incorrect

3240 G correct incorrect

3416.5 G correct incorrect

332.0 mT correct incorrect

301.5 mT correct incorrect

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. The C₂O₂^- radical anion possesses a rhombic g tensor with resonant field values of 1210.9, 1211.5 and 1213.3 mT at 34 GHz. Calculate the g values of the anion.

g₁ = 2.342; g₂ = 2.210; g₃ = 2.137 correct incorrect

g₁ = 2.652; g₂ = 2.198; g₃ = 2.108 correct incorrect

g₁ = 2.078; g₂ = 2.001; g₃ = 2.000 correct incorrect

g₁ = 2.006; g₂ = 2.005; g₃ = 2.002 correct incorrect

g₁ = 2.050; g₂ = 2.000; g₃ = 1.950 correct incorrect

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. A Cu(II)-bis(salicylaldoxime) complex bearing two strongly coordinated ¹⁴N nuclei produces the quadrupole values P_zz = -1.15, P_yy = 0.70, P_xx = 0.45 MHz in a hyperfine spectrum. Calculate the asymmetry parameter (η) and the quantity e²qQ/h.

η = 0.15; e²qQ/h = 1.3 correct incorrect

η = 0.22; e²qQ/h = -2.3 correct incorrect

η = 0.33; e²qQ/h = -0.3 correct incorrect

η = 0.87; e²qQ/h = -4.1 correct incorrect

η = 1.24; e²qQ/h = -0.7 correct incorrect

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. A surface trapped electron centre interacts with a nearby hydroxyl group on a metal oxide surface producing a quasi isotropic g value ≈ g_e. Given the principal ¹H hyperfine values were found to be A₁ = -2.5, A₂ = -2.5, A₃ = 8 MHz, estimate the electron-proton distance.

4.5 nm correct incorrect

6.87 x 10^-10 m correct incorrect

4.32 x 10^-10 m correct incorrect

2.8 nm correct incorrect

3.5 x 10^-10 m correct incorrect

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. The average distance between the equivalent equatorial protons and the unpaired electron in a vanadyl-pentaaqua complex, [VO^II(H₂O)₅], is 3.7 x 10^-10 m. Given that a_iso = 1.5 MHz and assuming the point dipole is a valid approximation, estimate the likely magnitude of the ¹H hyperfine A values.

A₁ = 0.0; A₂ = 0.0; A₃ = 5.0 MHz correct incorrect

A₁ = -0.06; A₂ = -0.06; A₃ = 4.62 MHz correct incorrect

A₁ = -0.12; A₂ = -0.12; A₃ = 0.24 MHz correct incorrect

A₁ = -1.6; A₂ = -1.6; A₃ = 2.8 MHz correct incorrect

A₁ = 0.1; A₂ = 0.1; A₃ = 2.5 MHz correct incorrect

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. For the rhombic spin system shown in Fig. 5.5, calculate the g value expected in the single crystal EPR spectrum when the orientation of B relative to the g frame is given by θ = 45° and φ = 30°.

g = 1.964 correct incorrect

g = 1.987 correct incorrect

g = 2.043 correct incorrect

g = 2.012 correct incorrect

g = 1.990 correct incorrect

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. For the rhombic spin system shown in Fig. 5.5, determine the values of θ and φ that will produce a peak in the single crystal EPR spectrum with g = 2.002.

θ = 25°; φ = 75° correct incorrect

θ = 0°; φ = 90° correct incorrect

θ = 45°; φ = 45° correct incorrect

θ = 0°; φ = 0° correct incorrect

θ = 90°; φ = 90° correct incorrect