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Title: Some new studies in the techniques of analytical atomic spectroscopy
Author: Sharp, Barry Leonard
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 1972
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A microwave excited, atmospheric pressure, argon plasma was investigated as a source for emission spectrometry. The electron temperature of the plasma was measured and the results employed to demonstrate that the bulk of the free electrons were in local thermodynamic equilibrium with the excited states of the argon carrier gas. The measured equilibrium temperature was 5680 K which was sufficient to enable the plasma to excite atomic states over eleven electron volts above the ground state. A plasma emission system was constructed, sampling being achieved by use of a platinum loop atomiser. The device proved extremely sensitive for a range of elements yielding detection limits down to 2.0.10¹³ g for Cd. The analytical precision was acceptable and preliminary studies indicated that interferences were not serious. Radiation signals obtained from the emission system were transient in nature and required integration for optimum precision of measurement. Initially capacitative integration was employed but later this was replaced by a photon counting system. The results obtained with photon counting were excellent and therefore a general investigation of the technique was undertaken. Photon counter design was studied, a new system constructed and theoretical work carried out to determine optimum system parameters. The application of the technique to atomic emission, atomic fluorescence and atomic absorption was investigated for both transient and continuous radiation signals. Experimental results suggested that in certain conditions long period integration might yield improved limits of detection. Theoretical signal to noise ratio expressions were therefore developed in order to explain these results and to define more clearly how the various noise components affect the precision of measurement.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available