Ground state characterization of the luminescent "molecular ruby" with Kalpha RXES, HERFD-XANES and vtc XES.

The quest for new, sustainable, and photoactive complexes based on earth-abundant elements aims to replace their noble metal-based, expensive counterparts. The Cr-based "molecular ruby" exhibits unprecedented long-lived NIR luminescence with a quantum yield of 11 % in water. The high ligand field splitting allows the unusual for Cr(III) complexes 2T2g state. The complex was studied using ultrafast XES spectroscopy, showing a complex multiplet structure of the Kalpha1 emission line. A detailed ground state characterization of the molecule will be performed using RXES to understand observed spectral features and serve as calibration data for the fs-XES experiment. The obtained results will allow to characterize of the electronic structure of the new complex and help to develop this new group of complexes.