We observe preferential cavity-mode selection in spontaneous emission by oriented molecules at the surface of a microparticle. Polarization-analyzed images of a levitated microdroplet containing surface active molecules reveal a well-defined system in terms of molecular position and orientation. The measured fluorescence spectrum is compared with that of a semiclassical emission-rate-enhancement model that treats the coupling between an excited state and Mie resonances as an oscillating dipole interacting with its self-scattered field. By comparing results obtained with this theory with the relative strengths of TE to TM modes measured in the emission spectrum, we show that one can elucidate the heterogeneity of a particle from this resonant structure and determine the orientation of the emission moments relative to the phase boundary.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics