) t i n U . b r A ( L P ) t i n U . b r A ( L P ) t i n U . b r A ( L P (c) Up Down down down up down up Kim et al. Nanoscale Research Letters 2011, 6:405 http://www.nanoscalereslett.com/content/6/1/405 Page 6 of 8 (a) pristine-up pristine-down pristine (b) Up Down HT-110 HT-110-up HT-110-down ) t i n U . b r A ( L P ) t i n U . b r A ( L P ) t i n U . b r A ( L P HT-150-up HT-150-down HT-150 down HT-180-up HT-180-down down up up down up 650 Up Down 450 500 550 600 650 Wavelength (nm) 450 500 550 600 Wavelength (nm) up HT-130-up HT-130-down (d) HT-130 450 500 550 600 650 450 Wavelength (nm) (e) HT-160-up HT-160-down HT-160 Up Down (f) 500 550 600 Wavelength (nm) HT-180 650 Up Down 450 500 550 600 650 Wavelength (nm) 450 500 550 600 650 Wavelength (nm) Figure 4 PL spectra. The filtered-up and filtered-down (a) pristine rubrene NPs and (b) HT-110, (c) HT-130, (d) HT-150, (e) HT-160, and (f) HT- 180 rubrene NPs. Insets: Photographs of light emission for the corresponding rubrene NPs.