Sol-Gel Thin Films Immobilized with Bromocresol Purple pH-Sensitive Indicator in Presence of Surfactants

Figure 6

Absorption spectra of immobilized BCP/SDS at different pH values (1–13.5): (a) pH 1–10, 𝜆_max = 435 nm, (b) pH 1–4.5, 𝜆_max = 535 nm, and (c) 10.5–13.5, 𝜆_max = 595 nm.