Dr. Yoshizumi Kajii, Professor

Dr. Yoshizumi Kajii

OH reactivity measurement by laser pump and probe technique and its application to diagnosis of air quality

Tokyo Metropolitan University

*The organization and the title are those when awarded


  • 日本語
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To reveal reaction mechanism of the atmosphere or diagnosis air quality we proposed a new methodology to get equivalent information of reactive species without systematic observation of all kinds of VOCs. We enhanced OH concentration in real atmosphere using pulse laser and measured the decay of OH using laser induced fluorescence technique. We successfully developed the system to measure OH reactivity using laser flash pump and probe technique. Using this instrument we observed both urban and semi-urban air with simultaneous analysis of reactive species. Interestingly systematic under estimation of OH reactivity was obtained. It ranged from 25 to 50 % of total OH reactivity depending on the season and also locations. It indicates a considerable amount of missing sink of OH that we do not consider yet even though we counted more than 100 kinds of chemical species.

Research summary

The study of Dr. Kajii focused on the quantitative determination of unidentified reactive trace chemical species by measuring the decay of artificially generated hydroxyl (OH) radicals. The proposed research has direct on the huge problem of automobile exhaust emissions.