Fluorescent carbon dots (C-dots) were synthesized by a facile method containing liquid N-2 treatment and centrifuge processes. The photophysical properties of the C-dots in an aqueous solution were examined at various conditions such as concentration, temperature, pH and excitation wavelength by using UV-vis absorption, fluorescence and time-resolved fluorescence spectroscopies. The C-dots emitted a broad fluorescence between approximately 350-550 nm and their fluorescence was tuned by changing excitation wavelength. The as-prepared C-dots were applied to Fe3+ detection from aqueous solution. Spectroscopic data revealed that the as-prepared C-dots were used to detect Fe3+ in the range of 12.5 mu M to 100 mu M as a fluorescence sensor. (C) 2015 Elsevier B.V. All rights reserved.