Ruth B
MEDIS-Institut, Gesellschaft für Strahlen- und Umweltforschung mbH München, Neuherberg, Federal Republic of Germany.
Radiat Environ Biophys. 1990;29(1):57-73. doi: 10.1007/BF01211235.
The scattering coefficient of yellow spruce needles exceeds that of green needles by a factor of 2, whereas the fluorescence efficiency is approximately equal for both needle colours. As shown by the angular distribution the fluorescence light is diffusely emitted. However, the scattered light consists of a diffuse and a reflecting portion below 20 degrees with a ratio of the intensities of 1 : 2 at perpendicular observation (0 degrees). Control measurements show that in the rejection region the effective transmission of cut-off-filters commonly used to separate fluorescence light and excitation light exceeds the value calculated from the filter specifications by a factor of 100. Therefore, the portion of the scattered light in the measuring signal must be controlled if the fluorescence induction kinetics is measured from specimen of different colour. A device for the determination of the fluorescence induction kinetics is described which employs a He--Ne laser, a mechanically working shutter with an opening time of 4 ms for the excitation, and a computer for data storage and device control. Two filters select the fluorescence components at 685 nm and 730 nm and they reduce the portion of the scattered light in the measuring signal to 0.18% and 0.55%, respectively. In order to consider the temporal development of the fluorescence kinetics the sampling rate is reduced from 2 kHz to 1 Hz. From the data stored in the computer maximum value Fp, and steady-state-value Fs are determined for both fluorescence components. Measurements on 4-year-old spruce exposed to ozone-concentrations of 0, 300 ppb, 600 ppb, and 1000 ppb were repeated every week. With increasing concentration and duration of treatment Rfd = (Fp-Fs)/Fs was decreased for both fluorescence components. With the highest ozone concentration a reduction of Rfd of 23% and 24%, respectively, was obtained for the two fluorescence components after three weeks.
黑云杉针叶的散射系数比绿针叶的散射系数高出两倍，而两种针叶颜色的荧光效率大致相同。从角分布可以看出，荧光是漫射发射的。然而，散射光由低于20度的漫射部分和反射部分组成，在垂直观测（0度）时强度比为1:2。对照测量表明，在剔除区域，通常用于分离荧光和激发光的截止滤光片的有效透过率比根据滤光片规格计算的值高出100倍。因此，如果从不同颜色的样本测量荧光诱导动力学，必须控制测量信号中散射光的部分。描述了一种用于测定荧光诱导动力学的装置，该装置采用氦氖激光器、用于激发的开启时间为4毫秒的机械快门以及用于数据存储和设备控制的计算机。两个滤光片选择685纳米和730纳米处的荧光成分，它们将测量信号中散射光的部分分别降低到0.18%和0.55%。为了考虑荧光动力学的时间发展，采样率从2千赫兹降低到1赫兹。从计算机存储的数据中确定两种荧光成分的最大值Fp和稳态值Fs。每周对暴露于0、300 ppb、600 ppb和1000 ppb臭氧浓度下的4年生云杉进行重复测量。随着处理浓度和持续时间的增加，两种荧光成分的Rfd = (Fp - Fs)/Fs均降低。在最高臭氧浓度下，三周后两种荧光成分的Rfd分别降低了23%和24%。
