The fluorescence emission and excitation spectra, and polarization spectra, of fluorescein molecules in the cytoplasm of human lymphocytes, were studied with an improved method to investigate changes in the physical state of the cytoplasmic matrix. The intensities of fluorescein in fluorescence emission and excitation spectra in unstimulated and PHA-stimulated lymphocytes depended on the wavelength in measurement regions as well as polariza tion values. The fluorescence polarization values of PHA-stimulated lymphocytes were 10-15% lower than those of unstimulated lymphocytes from 500nm to 550nm in the emis sion wavelength. Similar results were obtained from 450nm to 480nm in the excitation wavelength. The study upon the influence of the intensity of exciting light on the fluorescence polarization values revealed that the fluorescence polarization values were independent upon the strength exciting light. The influence of scattered light and microstirrer on the fluorescence polarization values was negligible in the present measurement.
We calculated the polarisations of the emission cross sections of the 21S-31P and 21P-31D transitions of HeI by the two-level model for the collision energy below 20 keV, attributing the cause of alignment of the magnetic sublevels to the excitation mechanism assigned in a previous paper. Qualitative agreement between the calculated polarisations and the measured ones shows that noticeable variation of the observed polarisation with increasing impact energy is ascribed to rotation of the molecular axis following the change of scatter ing angle. The contribution of the secondary processes and the influence of the deviation of the symmetry axis of the atom from the internulear axis of the separating particles, to the polarisations were discussed.