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M.Sc. (Instrumental Chemical Analysis) / An investigation was undertaken into the analytical procedures and the identification of problem areas, for the certification of a new biological standard reference material supplied by the International Atomic Energy Agency, namely, a human hair sample designated as HH-I ...

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1. The effect of deviations from Beer's law on the precision of atomic absorption analysis has been examined from a theoretical point of view, and a function has been derived which makes it possible to evaluate quantitatively the effect of calibration curvature on the precision of analysis. The influence of incomplete sample volatilization on calibration curvature has been briefly investigated. 2. Possible error sources in atomic absorption spectrometry have been classified according to the "error function" (i.e., the dependence, upon transmittance T, of the uncertainty dT in a given transmittance measurement) with which they are associated. The magnitude of the contribution from each component function to the overall error function has been evaluated quantitatively, and it has been shown that the major component in nearly every case examined is that associated with the dynamic nature of the flame. Concentration ranges for optimum precision are suggested. 3. The effect of varying instrumental parameters on precision has been investigated, and generalized conditions for best precision have been ascertained. 4. The effect of an initial solvent extraction step on the precision of atomic absorption has been investigated for the elements copper and lead. It is shown that solvent extraction may be used to improve both the analytical sensitivity and the precision of analysis when very low concentrations of metal are determined. 5. The precision of analytical methods involving atomic absorption spectrometry has been studied, and the standard deviations compared with those obtained for the analysis of similar samples by means of a variety of other methods of analysis, both instrumental and classical.

The optical absorption line is 1s₁- 2p₀ at the absorption spectrum of arsenic doped silicon has been studied for various arsenic concentrations at four temperatures. The concentrations are .9 x 10¹⁵ cm⁻³, 1.7 x 10¹⁵ cm⁻³, 4.0 x 10¹⁵ cm⁻³ and 1.5 x 10¹⁶ cm⁻³, the temperatures are 4.2°K, 53°K, 77°K, and 90°K. Spectrometer broadening was accounted for in the observed line-widths. There was observed two temperature independent broadening mechanisms, concentration and strain broadening. Two temperature dependent broadening mechanisms were observed, phonon broadening and the statistical Stark effect. The five, broadening mechanisms are believed to account for the total line-width through the use of the Voigt analysis half-breadth method. A shift of the peak position with temperature was noted and a possible explanation presented. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

In this thesis a theoretical study is made of the resonance spectra of the B¹¹ nuclei in a single crystal of Kernite (Na₂B₄0₇.4H₂0) whose, quadrupole moments interact with the electric field gradient at the nuclear sites in the crystal in the presence of an external magnetic field when the magnetic and quadrupole interaction energies are comparable. Using the results of the high field work of Waterman and Volkoff, energy levels and transition frequencies have been calculated numerically using the University of British Columbia ALWAC-III-E digital computer over a range of magnetic fields in the region intermediate between the limiting cases of pure quadrupole energy levels slightly perturbed by magnetic interactions and Zeeman energy levels slightly perturbed by quadrupole interactions. The magnetic field was taken to be oriented in the plane perpendicular to the two-fold symmetry axis of the crystal and the calculations were carried out for different orientations of the external magnetic field in steps of 30°. A general theory has been developed for the calculation of signal intensities in the case of crossed coil spectrometer (induction method) and has been applied to the present case. The signal intensities for absorption type spectrometers are proportional to the transition probabilities, and results are given for the case of Kernite which enables one to compare the expected signal intensities of absorption spectrometers with those of induction spectrometers. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

An investigation has been made into the possibility of observing optical transitions (in the 100-micron region) between the ground state of a donor impurity In silicon and the remaining five states of the {1s} set introduced by Kohn and Luttinger. While such transitions are forbidden in the usual effective mass approximation, it is found that application of corrections to the effective-mass wave functions leads to an enhanced transition probability. Under- the assumption of a simple cubic lattice of impurities, the calculated absorption coefficient is of the order of 10 cm[power -1] at an impurity concentration of 1 x 10[power 18] cm[power -3], and falls off exponentially with decreasing impurity concentration. An upper limit is placed on the region in which the transition should be observable by the broadening of the 2s-2p impurity band. It is estimated that for concentrations greater than 5 x 10[power 18] cm[power -3] the transition of interest will be obscured. The calculated values of the absorption coefficient are probably only accurate to within, one, or even two, orders of magnitude, because of the approximations involved. However, there would appear to be no firm theoretical reason why the 1s[superscript (0)] → 1s[superscript (5)] transition should not be observed. / Science, Faculty of / Physics and Astronomy, Department of / Graduate