摘要
在非晶态PMMA膜中,p—二甲氨基苄叉丙二腈的荧光产率随温度升高而减小.在φ_F对t的曲线上,在105℃和45℃处有两个拐点,它们分别与PMMA的玻璃化转变和β-转变相对应。在低温区,lgφ_F和温度T之间有好的直线关系,表明由于甲基运动引起的δ—转变发生在一个较宽的温度范围.用热膨胀法测得的PMMA自由体积与荧光探针的无辐射失活速度之间的关系符合方程K_(nr)=K_(nr)~0exp(—v_0/bv_(?)).从我们实验中得到的K_(nr)对v_f^(-1)直线,可求出荧光探针的本征无辐射失活速度K_(nr)~0=5.71×10^(11)秒^(-1)和特定常数b=1.94.
In amorphous PMMA film, the fluorescence quantum yield of [p-dimethylamino benzylidenel malononitrile decreased with increasing temperture. Two break points in the φ_F vs. t plot occured at 105℃ and 45℃ , which correspond to the glass transition and β-transition of PMMA respectively. At the lower temperature there was a good linear correlation between lgφ_F and t. The result showed that the δ-transiton caused by methyl group motion occured within wide temperture range. The relationship between the nonradiative decay rate of the probe and the free volume of PMMA obtained by dilatometry was in accordance with the following equation k_(?)=k_(?)~0exp(-v_0/bv_f) From our straight line, the intrinsic nonradiative decay rate (k_(?)~0) and the constant (b) of the probe were 5.71×10^(11)s^(-1) and 1.94.
