We present ultrafast-depopulation-dynamics of higher-lying-excited-states using femtosecond fluorescence up-conversion techniques for two near-infrared (NIR) tricarbocyanine dyes (IR144 and IR140) in primary alcohols. With visible excitation wavelengths, such dyes show two distinct emission-bands with large peak wavelength difference: one at the visible region: S₂→S₀, and the other at NIR region: S₁→S₀. We show that exact band-positions, intensities, and fluorescence-decay-timescales (τ) depend strongly on viscosity and polarity of solvents. Interestingly, though the faster component of τ increased for IR144 with increasing viscosity and chain-length of alcohols, the reverse was seen for IR140, indicating the possible formation of ion-pair of IR140 with alcohols.

我们使用飞秒荧光上转换技术针对伯醇中的两种近红外（NIR）三碳菁染料（IR144和IR140），提出了高激发态的超快灭绝动力学。在可见的激发波长下，此类染料显示出两个不同的发射带，它们具有较大的峰值波长差：一种在可见光区域：S ₂ →S ₀，另一种在近红外区域：S ₁ →S ₀。我们显示出精确的条带位置，强度和荧光衰减时间标度（τ）很大程度上取决于溶剂的粘度和极性。有趣的是，尽管IR144的τ的更快成分随醇的粘度和链长的增加而增加，但IR140却相反，这表明IR140与醇可能形成离子对。