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Type of Document	Dissertation
Author	Marshall, Royal R.
URN	etd-01152004-092735
Persistent URL	http://resolver.caltech.edu/CaltechETD:etd-01152004-092735
Title	I. The rate of recombination of iodine atoms. II. Some studies of the trace quantities of lead, uranium, and thorium in marine carbonate skeletons
Degree	PhD
Option	Chemistry
Advisory Committee	Advisor Name Title Norman Davidson Committee Chair Claire Patterson Committee Member Harrison Brown Committee Member
Keywords	None
Date of Defense	1955-01-01
Availability	unrestricted
Abstract NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. PART I. The rate constants for the homogeneous recombination of iodine atoms in the gas phase, I + I + M [...] I[subscript 2] + M, d[I[subscript 2]] /dt = k [I][superscript 2] [M], have been measured for the gases M = A, [...]-C[subscript 5]H[subscript 12] and [...]-C[subscript 5]H[subscript 12] at room temperature. The rate constants are 4.2 ([...]0.4) x 10[superscript 9], and 65 ([...]6) x 10[superscript 9] liter[superscript 2]mole[superscript -2]sec[superscript -1], respectively. In these experiments and those with iodine solutions, a short, intense pulse of light from a flash lamp dissociated 1-10% of the iodine molecules in a reaction cell. The photoelectric cell response to a light signal modulated with the change in the iodine atom concentration was amplified and used as the vertical deflection input of an oscilloscope. The oscilloscope trace, a direct indication of the subsequent recombination observed during periods from 0.0002 sec after the flash to as long as 0.01 sec, was recorded photographically. The rate constants for the recombination of iodine atoms in the liquids CC1[subscript 4] and [...]-C[subscript 7]H[subscript 16], d[I[subscript 2]]/dt = k [I][superscript 2], were found to be at room temperature 0.7 ([plus or minus]0.11) x 10[superscript 10] and 2.2 ([plus or minus]0.4) x 10[superscript 10] liter mole[superscript -1], respectively. The primary quantum yields in the solutions were found to 0.19 ([plus or minus]0.05) and 0.41 ([plus or minus]0.26), respectively. PART II. A procedure is described for the chemical isolation from carbonates of microgram quantities of lead, uranium, and thorium suitable for mass spectrometric analyses. The concentration of lead in a Jurassic belemnite as well as a Mississippian Spirifer has been found to be less than 1 ppm while for Strombus gigas, a living species of gastropod, the value 0.19[plus or minus]0.04 ppm was found. The uranium concentration in this gastropod was determined as 0.036[plus or minus]0.002 ppm. The isotopic composition of the lead from the Strombus gigas has also been determined and is compared to other analyses of "common" lead.
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