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International Center for Materials Nanoarchitectonics (WPI-MANA)

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[[Research Highlights Vol.5] Detecting caesium with naked eyes](https://mdr.nims.go.jp/datasets/42864198-0598-4000-beec-e4d85b1a61d0)

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2022/04/04 10:28 Detecting caesium with naked eyes| MANAhttps://www.nims.go.jp/mana/research/highlights/vol5.html 1/2Previous  Index  NextResearch Highlights[Vol. 5]Detecting caesium with naked eyes4 Mar, 2013'Micrometre-level naked-eye detection' of caesium ions, a major source ofcontamination in the vicinity of radioactive leaks, is demonstrated in amaterial developed by researchers in Japan.Figure : Photographs of fluorescence changes of a mixture of the phenolcompound and various carbonate salts after addition of a drop of methanol. (a)Fluorescence change of a powdered mixture of the compound and Cs2CO3 underUV irradiation (365 nm) after addition of a drop of methanol. (b) Photographs ofa mixture of the compound and various carbonate salts of other metals under UVirradiation (365 nm) after addition of a drop of methanol. (c) Photographs of thecompound with caesium cations on dirt under room light (left) and under UVirradiation (365 nm, right) after spraying with methanol. (d) Photographs of thecompound with caesiumcation particles on filter paper (diameter 110 mm) underUV irradiation (365 nm) after spraying with methanol.Radioactive caesium 137 has a half-life of 30.17 years, and its accumulation in organisms inexposed regions, such as around the Fukushima Daiichi nuclear plant, amplifies the hazard itposes. A new material reported by researchers in Japan may help. "We have developed molecularmaterials as an optical probe for caesium cation-containing particles with implementation based onsimple spray-on reagents and a commonly available fluorescent lamp for naked-eye detection inthe solid state," explain Jonathan P Hill, Katsuhiko Ariga and colleagues at the WPI-Internationalhttps://www.nims.go.jp/mana/research/highlights/vol4.htmlhttps://www.nims.go.jp/mana/research/highlights/index.htmlhttps://www.nims.go.jp/mana/research/highlights/vol6.html2022/04/04 10:28 Detecting caesium with naked eyes| MANAhttps://www.nims.go.jp/mana/research/highlights/vol5.html 2/2Center for Materials Nanoarchitectonics, Tokyo University and the Japan Science and TechnologyAgency (JST).The researchers based the probe on changes in the fluorescence of organic compounds calledphenols in the presence of alkali metals. They designed a substituted phenol compound with anelectron-accepting 4-nitrophenyl ether (4-NPE) group. The compound showed a distinctive greenfluorescence in the presence of caesium cations and methanol. In comparison, other alkali metalsgave rise to dimmer blue fluorescence.The researchers noted that the fluorescence peak shifted with increasing caesium concentration sothat the probe could be calibrated. The probe was sensitive to caesium concentrations of 1 part permillion. This is the concentration naturally occurring in the Earth's crust meaning excess to thenorm can be detected.Alongside molecular dynamics calculations these observations suggested the mechanism behindthe fluorescent behaviour, for which the geometry of the compound molecules and interactionsbetween different constituents seem key.As the authors suggest, "The availability of this and other similarly easily implemented tests forenvironmental contaminants is likely to increase the volume of data regarding rates ofcontamination around chemical and radiological hazards."Reference"Micrometer-level naked-eye detection of caesium particulates in the solid state"Taizo Mori, Masaaki Akamatsu, Ken Okamoto, Masato Sumita,Yoshitaka Tateyama, HidekiSakai, Jonathan P Hill, Masahiko Abe, and Katsuhiko ArigaJournal : Sci. Technol. Adv. Mater. [7 February 2013]DOI : 10.1088/1468-6996/14/1/015002AffiliationsInternational Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for MaterialsScience (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, JapanContact informationInternational Center for Materials Nanoarchitectonics(WPI-MANA)National Institute for Materials Science1-1 Namiki, Tsukuba, Ibaraki 305-0044 JapanPhone: +81-29-860-4710E-mail: mana-pr[AT]ml.nims.go.jphttps://samurai.nims.go.jp/profiles/mori_taizo?locale=enhttps://samurai.nims.go.jp/profiles/jonathan_hill?locale=enhttps://samurai.nims.go.jp/profiles/ariga_katsuhiko?locale=enhttps://www.tandfonline.com/doi/full/10.1088/1468-6996/14/1/015002