Photo-induced spin-state transitions in metal-organic nanomaterials have been vastly studied in recent years due to their possible applicability in nanophotonics and nanoelectronics. Spin-crossover (SCO) materials are transition metal compounds that exhibit the possibility of spin-state transitions, or switching, by external stimuli; such as the application of a magnetic field, change in temperature, change in external pressure, or induced light irradiation. Understanding the ultrafast relaxation dynamics of spin-state transitions, specifically of octahedral iron(II) complexes, has been a central research topic in coordination chemistry. Additionally, SCO nanoparticles’ size, along with their magnetic properties, open up the possibility of uses in biological applications, such as drug delivery, cancer treatments, and protein detection. In this project, the photoinduced dynamics of [Fe(HTrz)2(trz)][BF4] nanorods, within their thermal hysteresis loops, were to be studied by ultrafast nanosecond-resolved transient absorption spectroscopy, specifically with pump-probe Nd:YAG nanosecond lasers; however, experimental setup for the pump-probe spectroscopy was necessary. The construction of a “flow cell” for pump-probe spectroscopy of the nanorods was carried out in order to allow a constant variable-temperature flow of colloidal nanoparticle solution during the spectroscopy. A set of two Nd:YAG nanosecond pulse lasers were reconstructed and repaired in order to carry out nanosecond-resolved pump-probe spectroscopy. Additionally, the synthesis of [Fe(HTrz)2(trz)][BF4] nanorods was completed by the ‘reverse-micelle’ technique in order to tune particle size during the initial synthesis. The nanorods were characterized by transmission electron microscopy (TEM) in order to ensure the synthesis could produce nanoparticles with rod-shaped morphology. Further modifications were implemented to the synthesis, based on the results given by the TEM imaging.

Photo-induced phase transitions of spin-crossover nanoparticles within the thermal hysteresis loop

253rd National Meeting (2017)

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