Transient absorption measurements on Zn3N2 colloidal quantum dots

These transient absorption data were acquired from 3 samples of Zn3N2 colloidal quantum dots with different diameters using a system comprising a Helios (Ultrafast Systems LLC) spectrometer, an ultrafast Ti:sapphire amplifier system (Spectra Physics Solstice Ace) and an optical parametric amplifier (Topas Prime) with an associated NIR-UV-Vis unit. This system generated 100 fs pump pulses at 375 nm with a beam diameter of 240 μm. The pulse energy could be reduced using a series of reflective neutral density filters to give pump fluences from 1×1014 to 3.5×1015 photons·per cm2 per pulse. A white light continuum generated by the same laser system which was used as the probe to record changes in absorption between 430 and 913 nm. The samples were magnetically stirred to avoid photocharging effects during the measurements. Steady state absorbance spectra were acquired periodically to monitor and account for changes in absorbance due to oxidation of the Zn3N2 QDs.本实验所获得之瞬时吸收数据，源自于三种不同直径的Zn3N2胶体量子点样本，通过一套由Helios（Ultrafast Systems LLC）光谱仪、超快Ti:sapphire放大系统（Spectra Physics Solstice Ace）以及光学参量放大器（Topas Prime）构成的综合系统收集。该系统产生波长为375 nm、脉宽为100 fs的泵浦脉冲，光斑直径为240 μm。通过一系列反射式中性密度滤波器，可降低脉冲能量，从而实现泵浦荧光从1×10^14至3.5×10^15光子/厘米²/脉冲的调节。作为探测光源，同一激光系统所产生之白光连续谱，用于记录430至913 nm范围内吸收变化。为避免测量过程中产生光电充电效应，样本以磁力搅拌方式保持均匀。定期采集稳态吸收光谱，以监控并解释Zn3N2量子点氧化引起的吸收变化。