Figure 4
Typical SERS spectra of arsenate using various Ag/GL substrates as active substrates. (A) SERS spectra of arsenate: (a) 0 μg·l-1 (background) and (b) 300 μg·l-1 on Ag/GL-1/0.5-25 substrate; and (c) 0 μg·l-1 (background) and (d) 250 μg·l-1 on Ag/GL-5/2.5-18 substrate. (B) SERS spectra of 200 μg·l-1 arsenate on various Ag/GL substrates prepared in 5/2.5 mM AgNO3/BuNH2 ethanolic solution at different reaction times: (a) 2 h, (b) 3.5 h, (c) 5 h, (d) 9 h, (e) 18 h, (f) 25 h, (g) 31 h, and (h) 40 h. The samples were air-dried before SERS measurements. The spectra were shifted vertically for clarity but the relative intensity was kept unchanged except for the curve a in (B).