Chromium(III) offers a convenientplatform on which to carry out fundamental research in transition metalphotophysics due to its relatively simple electronic structure under highsymmetry, as well as the numerous photophysical studies on this ion in theliterature.  Previously, we employedultrafast transient absorption spectroscopy to monitor the nonradiativerelaxation in tris(acetylacetonato)chromium(III).  Excitation into 4T2,the first spin-allowed ligand field excited state, was followed by ultrafastintersystem crossing (t < 100 fs) into the lowest-energy excited state, 2E.  Vibrational cooling within this state thenproceeds with t = 1.1 � 0.1 ps.  We haveexpanded on these initial efforts to a series of high symmetry photostablecomplexes (i.e. tris-chelated derivatives of acetylacetonate) in an attempt toelucidate the mechanism of ultrafast intersystem crossing in these complexes.Current work also includes studies of lower symmetry (C2V) as wellas spin-exchange complexes of chromium(III). This presentation will cover the most recent results from this line ofresearch.

Ultrafast nonradiative dynamics
of chromium(III) complexes

239th National Meeting (2010)

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