Methods to calculate Raman and fluorescent radiation emitted from irregular particles

Raman and fluorescence studies have applications in virtually all fields of science. In particular, Raman lidar measurements can provide us with useful information about various atmospheric constituents, such as water vapor mixing ratio, cloud water content, and specific gaseous species. In Raman scattering, molecules embedded in dielectric particles radiate light with a shifted wavelength compared with the incident light. In our study, we used both DDA and FDTD methods to calculate Raman scattering by molecules embedded in small particles. Our methods can also be used for fluorescence studies. Our results for spherical particles agree quite well with analytic results for particles with size parameter of up to 20. It is also demonstrated that the angular distribution of Raman scattering depends on both the size and shape of the particle, and location of the molecules in the particle. As a result of this study, it is possible that Raman lidar measurements can be interpreted in other ways and thus can provide more information about atmospheric constituents.