| 摘要 |
PURPOSE:To enable the satisfactory execution of recording and reading of informations by using laser beams of the same wavelength, by a method wherein specified dyestuff and dyestuff absorbing a light of a specified wavelength are borne on the same substrate. CONSTITUTION:The dyestuff expressed by a formula (I) and the dyestuff absorbing a light of a wavelength 760-850nm are borne on the same substrate. In an optical information medium having such a construction, recording, reproduction or erasure is conducted by using laser beams of a wavelength 760-850nm. In the formula, Z<1> and Z<2> denote alkyl, aryl or alkenyl, Q denotes N or C-R<6> (R<6> denote H, alkyl or aryl), R<1-> R<3> denote alkyl, aryl and alkenyl, X<-> denotes a negative ion, G denotes a group for connecting with N-R<3> to form a five- or six-membered ring, and L denotes a trivalent group formed of five methine groups or substituted methine groups so connected as to form conjugated double bonds. The dyestuff being preferable as absorbing the light of 760-850nm is expressed by a formula II. |
