Fluorescence emission spectra of CdS QDs prepared with different hexametaphosphate
concentrations as stabilizers (a: 1 mmol/L, b: 2 mmol/L, c: 5 mmol/L, d:
10 mmol/L, e: 20 mmol/L, f: 40 mmol/L). Reaction condition: 10 mmol/L Cd2+ cations
and 6 mmol/L S2− ions.