Photofunctional properties of molecular and hybrid materials often emerge from interactions among electronic, vibrational, spin, structural, and environmental degrees of freedom. Because these interactions evolve over timescales ranging from femtoseconds to milliseconds, observations within a single temporal window rarely provide a complete mechanistic picture. In this presentation, I will introduce a multiscale time-domain spectroscopic approach that combines ultrafast transient absorption and infrared spectroscopy with time-resolved photoluminescence and microsecond-to-millisecond kinetic measurements.

Ultrafast spectroscopy reveals how nuclear motion, electronic redistribution, and structural symmetry breaking define the initial excited-state landscape. In photoresponsive metal complexes and carbazole-based dendritic emitters, these measurements clarify how molecular flexibility, symmetry, and spatially heterogeneous electronic coupling govern excited-state localization and charge-transfer character. Extending the observation window to the nanosecond-to-millisecond regime enables the characterization of spin conversion, energy transfer, and nominally nonemissive states that cannot be directly identified from steady-state emission. Lanthanide complexes provide a representative example, in which time-resolved population analysis uncovers hidden intermediate states that control sensitization, energy migration, and nonradiative deactivation.

These studies demonstrate that photofunctionality is not determined by a single excited state or elementary rate constant. Rather, it arises from the sequential and competitive evolution of coupled states across multiple temporal and energetic scales. Multiscale time-domain spectroscopy therefore provides a general framework for connecting microscopic excited-state dynamics with macroscopic optical function and for extracting molecular design principles for emerging photofunctional materials.

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Meeting ID: 508 144 0931

Seminar hosts: Juraj Krsnik i Borna Radatović