Polytechnic University of Valencia Congress, Ampere 2019

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Satoshi Horikoshi

Last modified: 11-10-2019


The German chemist Theodor Grotthuss was the first to formulate the first law of photochemistry in 1817; he postulated that a reaction could be driven by light when the energy of light is absorbed by molecules [1]. After that, photochemistry has greatly contributed to the development of photography. In addition, second laws of photochemistry (Stark-Einstein law) was enacted, and these two laws have elevated photochemistry as an academic (science) discipline over the last one hundred years. In addition, because of advances in light sources and various devices (engineering), such materials and processes as photocatalysts, organic solar cells, photopolymerization, quantum dots, and photochromism (among others) are currently being applied in various other fields.                The next significant surge in chemistry is microwave chemistry wherein microwaves, which represent electromagnetic waves other than light, were introduced as a driving force in the chemical reaction domain in the late 1980s. There are three characteristics in this chemistry when using microwaves. The first is the high heating efficiency caused by the energy of the microwaves that directly reach and are absorbed by the substance. The second is the selectivity with which a specific substrate is heated, while the third characteristic is the enhancement of chemical syntheses by the microwaves’ electromagnetic wave energy, often referred to as the microwave effect (or non-thermal effect). The phenomenon of the microwave effect (third characteristic) impacting chemical reactions has been summarized in much of the relevant literature, however, the reason why the microwave effect has not been clarified to anyone’s satisfaction is that the term microwave effect in microwave chemistry includes numerous factors. In order to fix microwaves in the chemical field, it is urgent to develop laws of “microwavechemistry”, and to do it is necessary to systematization against the phenomenas of electromagnetic waves for materials and reactions.         One of the reasons for the dramatic growth in photochemistry is the development of high power laser technology. In recent years, coherent semiconductor generator with the generating high power microwaves have become easy to get, so “microwavechemistry” can proceed to the next stage. We examined that the phenomena as microwave electromagnetic waves in chemical reactions by using a semiconductor generator and a power sensor. And, it clarified that the reaction rate and yield of a very small part of the chemical reaction change with the unique phenomenon to electromagnetic waves [2]. On the other hand, generally, as plants, enzymes, biological substances temperature rises, it inhibits growth and reaction. This phenomenon was used to overcome the electromagnetic wave effect. We have succeeded in improving these activities by irradiating weak microwaves which do not increase these temperatures [3]. If microwave heating is given to them, it will work negatively. In this invited presentation, it introduces the possibility of electromagnetic wave effect(s) in these and explain its industrial application.


microwave science, electromagnetic wave effect, Semiconductor generator, microwave chemistry, microwave biology

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