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I. The rate of recombination of iodine atoms. II. Some studies of the trace quantities of lead, uranium, and thorium in marine carbonate skeletons

Marshall, Royal R. (1955) I. The rate of recombination of iodine atoms. II. Some studies of the trace quantities of lead, uranium, and thorium in marine carbonate skeletons. Dissertation (Ph.D.), California Institute of Technology.


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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.


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.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Major Option:Chemistry
Thesis Committee:
  • Davidson, Norman (chair)
  • Patterson, Claire
  • Brown, Harrison
Defense Date:1 January 1955
Record Number:etd-01152004-092735
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:181
Deposited By: Imported from ETD-db
Deposited On:16 Jan 2004
Last Modified:25 Dec 2012 14:58

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