Fig. 3

Raman spectra and optical microscopic image. Raman spectra of a K₁₂[Bi(H₂O)P₅W₃₀O₁₁₀]·26H₂O, b poly(allylamine hydrochloride), and c–f I at different vertical positions at the yellow spot of the optical microscopic image. Yellow bar shows the scale (1 mm). The axial depths of the focal spots are c 0 μm, d 10 μm, e 20 μm, and f 30 μm from the crystal surface. The intensities of (a) and (c–f) were normalized with the band at ca. 970 cm⁻¹. Note that the increase in relative intensity of the band assignable to PAA (1350–1450 cm⁻¹) from (c) to (d–f) is probably due to the washing of the crystal with water prior to measurement to remove the PAA which adsorbed from the synthetic solution onto the crystal surface