Lonie, William

2018-01-31T11:22:26Z

2018-01-31T11:22:26Z

1950

Examination has bean made of the ohotooxidation, in visible light, of chlorophyll preparations, deposited on various solids, by means of the direct measurement of oxygen pressure decrease.

Rates of oxidation were very low on glass, zinc oxide, aluminium oxide, ferric oxide, and on talc, but were some five to ten times more rapid on thallous bromide and thallous iodide. The maximum quantum efficiency on glass in light of wave length 4358 A.U. was of the order 10⁻², increasing slightly with decreasing film thickness.

Chromatographic and solvent partition separation methods applied to two chlorophyll preparations enabled two main fractions to be examin¬ ed, a yellow carotene fraction and the green chloro¬ phyll fraction. Cn thallous bromide, the oxygen to carotene and the oxygen to chlorophyll molar ratios in oxidation were unity. The chlorophyll fraction of a second sample showed an apparent oxygen to chlorophyll molar ratio of approximately two. Oxidations were partly reversible by simple pressure reduction. For one chlorophyll preparation, a limit of oxygen pressure of approximately 0.1mm. was established, below which no oxidation occurred.

A possible mechanism has been discussed in relation to the experimental results and to the general nature of such preparations.

http://hdl.handle.net/1842/26698

The University of Edinburgh

Annexe Thesis Digitisation Project 2017 Block 15

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Studies on the photo-oxidation of chlorophyll

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PhD Doctor of Philosophy