Kinya Kumazawa

A Three-Dimensional Fluorescence Analysis of the Wings of Male Morpho sulkowskyi and Papilio xuthus Butterflies

Abstract Fluorescence properties from the wings of male M. sulkowskyi and Papilio xuthus butterflies were investigated for the first time over a wide range of excitation and emission wavelengths using a three-dimensional (3-D) fluorescence method. From the 3-D plots of the pale blue region of the wings of M. sulkowskyi, four contour peaks were observed. On the other hand, from the yellow region of the wings of Papilio xuthus, one peak was observed. The origins of these contour peaks are discussed based on a comparison with standard pigments. Of the four contour peaks seen for M. sulkowskyi, a specific peak (A), located at an excitation wavelength of about 325 nm and an emission wavelength of about 410 nm, was thought to be mainly due to a mixture or compound of three pteridine pigments (i.e., biopterin, pterin and isoxanthopterin). The single specific peak observed for Papilio xuthus, located at an excitation wavelength of about 400 nm and an emission wavelength of about 470 nm, was thought to be due to the Papiliochrom II pigment. Based on these results, the possibility of using 3-D fluorescence analysis as a tool for classifying butterflies is briefly described.

FLUORESCENCE FROM WING OF MORPHO SULKOWSKYI BUTTERFLY

Fluorescence from various parts of a wing of a male butterfly, Morpho sulkowskyi ( Morpho species), was investigated using a microspectrophotometer. From the central (blue color) region of the wing, fluorescence was observed for the first time in this species when irradiated with ultraviolet (UV) or visible light. On the other hand, the distal tip (black color) of the wing was not fluorescent. Further microscopic studies also showed that the fluorescence spectra of the upper (dorsal) and the lower (ventral) surfaces of scales, which were obtained from the fluorescent central region of the wing, were different, having fluorescence peaks at 520 nm and 470 nm, respectively.

Time-Resolved Fluorescence Studies of the Wings of Morpho sulkowskyi and Papilio xuthusButterflies

Abstract Fluorescence from the wings of male Morpho sulkowskyi and Papilio xuthus butterflies has been investigated for the first time using time-resolved fluorescence spectroscopy. Intensity of emission spectra from the wings of Papilio xuthus decreased with increasing delay time after the application of exciting laser pulse and the intensity peak showed an interesting red shift from 480 to 520 nm. In contrast, such a peak shift was not observed from the wings of Morpho sulkowskyi. The decay times obtained from the wings of Morpho sulkowskyi and Papilio xuthus were given by two components, respectively; those of the former at 510 nm were about 0.545 ns and 2.74 ns and those of the latter at 480 nm were about 0.490 ns and 2.10 ns. Based on these results, the possibility of using time-resolved spectroscopy as a tool for the classification of butterflies is described along with a brief discussion of the origin of the 520 nm peak observed for Papilio xuthus.

Fluorescence from cover and basal scales of Morpho sulkowskyi and Papilio xuthus butterflies

Fluorescence from the cover and basal scales on a wing of the male Morpho sulkowskyi butterfly was investigated using microspectrophotometry (MSP). From these scales, two fluorescence peaks were observed with a different intensity ratio between the cover and the basal scales. The fluorescence spectrum from the cover scale had a peak around 440 nm, which was stronger than a peak around 490 nm, while the intensities of these peaks were reversed in the basal scale. In addition to this butterfly, fluorescence from the wing of the male Papilio xuthus butterfly was studied with a result that there was no distinct difference in the fluorescence spectra between the cover and the basal scales. On the basis of these results, a possibility to use the MSP method as a tool for the classification of the butterfly is briefly described.

Modification of Ionization Potential of Poly(ethylene dioxythiophene):Poly(styrene sulfonate) Film by Acid or Base Treatment

We studied the effects of surface treatments on the surface electronic state of the poly(3,4-ethylene dioxythiophene):poly(4-styrene sulfonate) (PEDOT:PSS) film. The surface treatments performed were immersion of the PEDOT:PSS film in an acid or base solution, and the exposure of the PEDOT:PSS film to acid or base vapor. The ionization potential (Ip) of the PEDOT:PSS film is modified between 4.5 and 5.3 eV by surface treatments. Ip tends to be increased by acid treatment, although it tends to be decreased by base treatment. Because Ip is modified even by brief treatments, the modification is thought to result from surface condition changes. Measurements using X-ray photoelectron spectroscopy (XPS), resistivity, and optical absorbance revealed that an electric double layer might have been formed on the surface of the PEDOT:PSS film by the treatment. The electric double layer shifts the vacuum level. Assuming the formation of an electric double layer, we can describe Ip modification by the treatment.

Hue Change in Interference-Colored Fibers with an Alternating Multilayer Structure

The change in hue of interference-colored fibers, which are consisting of alternating multilayer structure of poly(ethylene terephthalate) (PET) and polyamide 6 (Ny-6) covered with PET clad, was investigated in comparison with that of ordinary dyed PET fibers. The results indicated that, when an incident light was applied to the dyed PET fibers either parallel to or vertical to the fiber axis, although the chromaticness index (a*, b*) plotted on a*- b* coordinates changed in distance from the origin as the receiving angle β was increased from -30° to 70°, no change was observed in its track direction. On the other hand, the track of the chromaticness index for the interference-colored fibers changed substantially between incident lights parallel to and vertical to the fiber axis. In the former case, the chromaticness index plots were virtually all near the origin even though β was varied and tended to move substantially away from the origin in the range of specular reflection angles between 44° and 46°. In the latter case, however, the track of the chromaticness index moved counterclockwise in an arc shape from the second quadrant to the third and fourth quadrants with increasing β, clearly indicating a substantial change in hue. The interference-colored fibers were regarded as an alternating multilayer structure, and their reflection spectra were simulated taking into account the refractive index anisotropy (birefringence) of PET and Ny-6. The chromaticness index was found from the data thus obtained and plotted as coordinates in the same way as described above. As a result, the index was evaluated on the basis of an analysis of the simulation results and its track was plotted on the a*- b* coordinates. It was observed that the tendency of the chromaticness index track relative to the change in β was nearly the same as that seen when an incident light was vertical to the fiber axis. It is thought that the change in hue of the interference-colored fibers due to β is mainly attributable to the variation in the length of the optical path in their alternating multilayer structure.