Figure 1.

The absorption spectra of the lactone-rhodamine B (L-RB) film after it was immersed to a NaTPBF solution (pH 4.0, adjusted with a 0.1 M CH₃COOH/CH₃COONa buffer solution) for 30 min, respectively. Concentration of NaTPBF: (1) 0 µM, (2) 1.0 µM, (3) 5.0 µM, (4) 10.0 µM, (5) 50.0 µM, and (6) 100.0 µM.