确定气态饱和胺分子振子强度与荧光辐射速率常数的关系探讨

在此研究中,采用一系列具有相似结构的气态饱和单胺和二胺作为研究对象,应用Gaussian03计算化学软件,在DFT/B3LYP水平上,使用6-311+G(d)基组优化处于基态的胺分子结构并使用CIS/6-311+G(d)优化处于激发态胺分子的结构,计算激发能量、激发波长,以及S1←S0振子强度f。通过查得文献中已有的气态饱和胺的荧光寿命以及得到的荧光辐射速率常数实验数据,比较计算得出的振子强度f,得出结论:双胺的荧光寿命明显长于单胺;若f=0,表明跃迁禁阻,像DMPZ,DABCO,它们的荧光寿命很长,超过了770ns;若f>0,则允许跃迁,饱和胺分子荧光寿命小于60ns。可由计算得出的f值,初步判断荧光物质在UV辐射作用下的荧光寿命长短。并得到振子强度f与荧光辐射速率常数线性关系。与基态分子结构比较,激发态的饱和胺分子结构发生改变。

Determination of the Relationship between the Oscillator Strengths and Fluorescence Radiative Rate Constants of the Gaseous Saturated Amines

In this research,a series of saturated monoamines and diamines with similar molecule structures are investigated.The Gaussian03 DFT/B3LYP/6-311+G(d) method was carried out to optimize the molecular structures in ground state.CIS/6-311+G(d) was used to optimize the S1 molecular structures and calculate the S1←S0 oscillator strengths(f values).The excitation energies,excitation wavelengths and S1←S0 oscillator strengths were calculated.The calculated oscillator strengths with the experimental lifetimes and radiative rate constants were compared.It concluded that the fluorescence lifetimes of diamines are much longer than that of monoamines.If f=0,for example,DMPZ and DABCO,the transition is forbidden and their fluorescence lifetimes exceed 770ns.If f>0,the transition is allowed and the fluorescence lifetimes of these amines are less than 60ns.Using f values can estimate the fluorescence lifetimes under UV radiation.The oscillator strengths(f values) are linear with the fluorescence radiative rate constants.The geometries of the excited state amines occur to change comparing to that of the ground state.