Fig. 5
From: Label-free upconversion nanosensor for water safety monitoring of permanganate and dichromate ions
(a) Cr2O72− (2–2000 µM) concentration dependent UCL spectra of UCNPs@SiO2 in aqueous solution, (b) Stern-Volmer plot (I0/I versus Cr2O72− concentration), (c) the UCL quenching efficiency of UCNPs@SiO2 against the concentration of Cr2O72−, the linear relationship plot of the UCL quenching efficiency for Cr2O72− concentration in the (d) 2–500 µM and (e) 500–2000 µM range, (f) plot of c/[(I0–I)/I0] versus concentration of Cr2O72−, inset showing simulated linearity correlation for Cr2O72− concentration in the 2–500 µM range, (g) UCL intensity of UCNPs@SiO2 with addition of various anions (2000 µM) in aqueous solution; Anti-interference properties of the UCNPs@SiO2 to detect Cr2O72− in aqueous solution, (h) UCL intensity of UCNPs@SiO2 with Cr2O72− (2000 µM) together with other individual anions (2000 µM), and (i) UCL intensity of UCNPs@SiO2 with the addition of Cr2O72− together with other mixed anions at a fixed 2000 µM concentration. (Note: integrated intensity of UCNPs@SiO2 UCL at 345 and 361 nm was used.)