(a) Direct photographs of Ag colloidal suspensions fabricated by pulsed laser irradiation of the Ag target in liquid solutions containing polysorbate 80 (V_polysorbate:V_water = 5% v/v–25% v/v). (b) and (c) The UV-visible absorption and photoluminescence (PL) spectra of the as-prepared Ag colloidal suspensions, respectively. The insets in panel (c) show the photographs of large-sized Ag colloidal suspension and Ag QDs solution under irradiation by a 254-nm UV lamp, respectively. (d) The peak intensities of the PL spectrum of Ag QDs at about 510 nm versus the time delay at room temperature. The insets show the photographs of Ag QDs under irradiations by a 254-nm UV lamp for a delay time at 12 h and about 400 h, respectively. (e) The typical TEM images of Ag QDs after keeping them in liquid for 500 h.