THE JOURNAL OF
PHYSICAL CHEMISTRY (Registered in U. 8. Patent Office)
VOLUME 63
(0Copyright, 1959, by the American Chemical Society)
JANUARY 23, 1959
NUMBER 1
INTRODUCTION TO THE SYMPOSIUM ON PHOTOCHEMISTRY OF LIQUIDS AND SOLIDS BY LAWRENCE J. HEIDT, la ROBERT S. LIVING ST ON,'^ EUGENE RABINOWITCH'~ AND FARRINGTON DANIELS'~ Receaved October 87, 1968
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A sub-committee of the National Academy of Sciences-National Research Council is charged with encouraging research which may ultimately lead to new ways of using solar energy directly as light, (ie., without preliminary conversion to heat). Photosynthesis and the growth of plants based on it are a remarkable and all-important example of such a utilization of sunlight. Are there no other photochemical reactions which could be used in this respect? There is 110 theoretical reason to exclude the possibility of energy storing photochemical reactions produced by sunlight, which would not require a living plant and a good agricultural soil. The members of this committee are listed as authors in the title of this introduction. They met in October, 1956, to try to evaluate the possibilities of using sunlight through photochemical reactions. It was evident a t once that much more fundamental research is needed, and so it was decided to call together world experts in this field, to exchange ideas and to decide which lines of research should be stimulated. Much of the fundamental research of photochemistry has been done on gases, but gaseous systems are too bulky for practical purposes; so it was decided to limit this symposium to fundamental research on the photochemistry of solids and liquids. The plan of a symposium on the Photochemistry of Liquids and Solids was approved by the National Research Council, and the National Science Foundation made a substantial grant for its support. Professor Lawrence J. Heidt organized and conducted the Symposium, which was held in the Endicott House in Dedham, Massachusetts from September 3 to 7, 1957. There were twentysix participants, including eight from Europe.
Although the committee was interested in encouraging photochemical research into practical utilization of solar energy and in getting new ideas which may eventually help to achieve this aim, the symposium carried no handicap of being restricted to matters directly related to such practical applications. I n addition to the twelve symposium papers, now published here in THISJOURNAL,there were thirteen other papers, which were more in the nature of reviews. All twenty-five contributions will soon be published together as a monograph. The contributions to basic photochemistry which follow may be grouped under four headings: (1) photochemical reactions in general, (2) fluorescence studies, (3) photochemical reactions involving chlorophyll, and (4)kinetic studies. Of the five inorganic photochemical reactions described, the photodecomposition of nitrosyl chloride dissolved in carbon tetrachloride, described by Neuwirth, seems to be of special interest for solar energy utilization, because it is an endothermic reaction, produced by a wide range of wave lengths present in sunlight, and leading to products which can be separated, stored and recombined a t a later time. Of the two products formed, the chlorine remains in solution, and the insoluble nitric oxide escapes. The two recombine later, when mixed, with the evolution of heat. Parker reports on studies of flash photolysis of uranyl oxalate and cobalt oxalate in which longlived intermediates were observed, and important information was gained concerning the efficiency of electron transfer reactions. I n a second report, Parker describes two transient products formed in the flash photolysis of methylene blue. Sivertz describes photochemical reactions between mercaptans and olefins and analyzes the role of free radicals in them.
(1) (a) Massachusetts Institute of Technology; (b) University of Minnesota; (01 University of Illinois; (d) University of Wisconsin.
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