NNR IN RAPIDLY ROTATED METALS By - Nottingham eTheses ...

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- 116 - this temperature we obtain a mean value for R of 0.65. This figure is somewhat lower than the value of 0.85 recorded for the solid state by Dickson. The discrepancy arises out of the higher values of T1 and K used in our calculation. We note that Kruger et al. demonstrated that there is quite considerable shielding of the cadmium ions in aqueous solutions. Therefore any determination of the absolute value of R is depend- ent upon the experimental Knight shift being corrected for such shielding effects in both the metal and the salt. 8.4.4 VARIATION OF L<strong>IN</strong>ESHAPE WITH ROTATION SPEED - Careful lineshapes of the resonances of 111Cd and 113Cd nuclei were measured from static samples using the same resonant frequency of 13.7 MHz. for both isotopes. The anisotropic Knight shift can be estimated by comparing the experimental lineshape to the theoretical frequency distribution 8(v) = K[2(v, - vo) + a]-l given by equation (2.11). Figure 8.3 shows the 113Cd absorption curve together with the theoretical powder lineshape predicted by g(v) setting a equal to 4.4 kHz. The 111 Cd absorption spectrum was the same as the 113Cd spectrum to within experimental error and hence gave an identical value for a. It is usual to define the anisotropic Knight shift, Kan as 3a Kan ° 2y o. (a measured in frequency units)
tv D Xm =o N O Ul- X- z N O FIGURE 8.2 : The 111Cd CJl w D ý8 f-fl NO =' D fourier transformed spectra of pure cadmium powder, static and rotated at three different frequencies about the magic axis
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NNR IN RAPIDLY ROTATED METALS By R.
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I wish to express my thanks to: ACK
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quadrupole relaxation. However theo
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2.3.5 Quadrupole Relaxation 26 (i)
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5.9 Sample Preparation 71 5.9.1 Cup
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1.1 BASIC THEORY -i- CHAPTER 1 INTR
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-3- Transforming to the rotating fr
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-5- lattice and T2 is the spin-spin
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and -7- Vd(t) f(w1)cos w't dw Sao -
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-9- where the terms represent the Z
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- 11 - If rii = nrij = (Xli + X2j +
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- 13 - In powdered samples a weak i
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- 15 - This contact term manifests
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- 17 - where 0 is the angle between
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- 19 - termed pseudo-dipolar. It is
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- 21 - the non-secular terms of the
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- 23 - to the lattice directly via
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- 25 - (2.25), can then be assumed
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- 27 - quadrupole moments to produc
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- 29 - where En are the Zeeman ener
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3.1 INTRODUCTION - 31 - CHAPTER 3 N
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Aý T. B a A"T"B " - 33 - It is a g
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(-Ur Ho FIGURE 3.1. : Co-ordinate s
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D, (t) = 331 2 + 3YI2 sin 2a 4 - 36
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- 38 - X (t) = cos a cos ßp + sin
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- 40 - 3.7 THE EFFECT OF ROTATION O
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- 42 - observations are inconsisten
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- 44 - that it apparently offered n
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- 46 - bearings suffer from instabi
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SI FIGURE 4.1 SCALE il cm : The con
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N to 9 . ýC 8 Ü7 Z w D 06 w ax U.
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- 50 - The rotors used in this work
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Ip IJýi O 1 t - 1 - 1 p OI ý I ý
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- 52 - at rotation speeds around 4
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- 53 - the manufacture of which was
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PTFE Tape_ FIGURE 4.7 rotors SCALE
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4.4.4 COMMENTS - 55 - For completen
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Clamp Pf-£-- SECTION II SECTION 11
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5.1 EQUIPMENT - 58 - CHAPTER 5 EXPE
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- 59 - the range ±1 V are digitise
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SCALE 3 cm j Cooling Gas ; tainiess
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Trensmitter EXL, FIGURE 5.3 : The s
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FIGURE $. 4 s The spectrometer prob
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Gas Tuning ransmi tter Input Receiv
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- 64 - phase can then be set so tha
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-66- The transient nuclear signals
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- 68 - 5.7.1 THE SOLID ECHO PULSE S
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- 70 - sequence may be repeated. In
Page 97 and 98: a° P/'rvu - 72 - p is the resistiv
Page 99 and 100: - 74 - combined with a low viscosit
Page 101 and 102: 6.2 RESULTS AND DISCUSSION - 76 - A
Page 103 and 104: IC 1 I. FIGURE 6.2 : Measured T1 va
Page 105 and 106: - 78 - TABLE 6.1. DEBYE TEMPERATURE
Page 107 and 108: - 80 - TABLE 6.2. RATIO OF TI VALUE
Page 109 and 110: - 82 - TABLE 6.3. DEPENDENCE OF T1
Page 111 and 112: - 84 - provides further evidence th
Page 113 and 114: - 86 - CHAPTER 7 EXPERIMENTAL RESUL
Page 115 and 116: - 88 - Lorentzian NMR lineshape of
Page 117 and 118: - 90 - at the top with epoxy glue.
Page 119 and 120: - 92 - (c) Bulk Susceptibility Effe
Page 121 and 122: - 94 - aluminium nuclei in the meta
Page 123 and 124: FIGURE 7.1 : 27A1 F. I. Ds and corr
Page 125 and 126: - 97 - TABLE 7.1. COMPUTED SECOND A
Page 127 and 128: - 99 - and Slichter(104) reported t
Page 129 and 130: - 101 - of this value would be requ
Page 131 and 132: N JL I F- 0 z J I0 0123456789 ROTAT
Page 133 and 134: -103- results obtained at a tempera
Page 135 and 136: T10 ms 3. O 2.5 2'C H 1"C o.. v 234
Page 137 and 138: 0 - 106 - CHAPTER 8 MEASUREMENTS ON
Page 139 and 140: - 108 - process for vanadium the me
Page 141 and 142: - 109 - in the same way to the prec
Page 143 and 144: Qv == , 2 28 kHz -111- which is sli
Page 145 and 146: - 113 - from Cerac Inc. (USA). The
Page 147: - 115 - 8.4.3 SPIN-LATTICE RELAXATI
Page 151 and 152: which gives K=0.048 an ± 0.002 - 1
Page 153 and 154: - 118 - Lifetime broadening alone g
Page 155 and 156: - 120 - cannot be spun at low tempe
Page 157 and 158: - 122 - 11. L. E. Orgel, J. Phys. C
Page 159 and 160: - 124 - 59. P. J. Randall, Ph. D. T
Page 161 and 162: - 126 - 101. H. R. Khan, J. M. Reyn
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