title: Unexpected variability of millennium green: structural color of Japanese jewel beetle resulted from thermosensitive porous organic multilayer.
abstract: The Japanese jewel beetle (Chrysochroa fulgidissima) is one of the beautiful beetles showing metallic green color that is kept over a millennium. This is a typical structural color resulting from a multilayer, frequently seen in insects. It was found that the elytra unexpectedly change the color from original green to blue or red by heating at 200 degrees C or by immersing in bromoform for over 1 month. This variability implies that the multilayer consists of a thermosensitive porous material. The color change induced by heating was accompanied with elytron shrinkage; the sensitivity of the reflection peak was -0.6 nm/ degrees C in 30-65 degrees C. The porous structure was determined by positron annihilation lifetime spectroscopy; the averaged pore radius was around 0.25-0.30 nm, which is close to the size of the bromoform molecule. These features prove the thermosensitivity and porous structure of the multilayer although in unusual environments.
authors.affiliation: L'Oréal Recherche, KSP R&D D-637, Kawasaki, Kanagawa 213-0012, Japan. JCD00765@nifty.com
authors.forename: Eiki
authors.initials: E
authors.lastname: Adachi
mesh_terms: D000818:Animals; D001517:Coleoptera / Q000033:anatomy & histology*; D003116:Color; D008027:Light; D013696:Temperature