Comprehensive investigation of the electronic excitation of W(CO)6 by photoabsorption and theoretical analysis in the energy region from 3.9 to 10.8 eV

High-resolution vacuum ultraviolet photoabsorption measurements in the wavelength range of 115-320 nm (10.8-3.9 eV) have been performed together with comprehensive relativistic time-dependent density functional calculations (TDDFT) on the low-lying excited sates of tungsten hexacarbonyl, W(CO). The higher resolution obtained reveals previously unresolved spectral features of W(CO). The spectrum shows two higher-energy bands (in the energy ranges of 7.22-8.12 eV and 8.15-9.05 eV), one of them with clear vibrational structure, and a few lower-energy shoulders in addition to a couple of lower-energy metal-to-ligand charge-transfer (MLCT) bands reported in the literature before. Absolute photoabsorption cross sections are reported and, where possible, compared to previously published results. On the basis of this combined experimental/theoretical study the absorption spectrum of the complex has been totally re-assigned between 3.9 and 10.8 eV under the light of spin-orbit coupling (SOC) effects. The present comprehensive knowledge of the nature of the electronically excited states may be of relevance to estimate neutral dissociation cross sections of W(CO), a precursor molecule in focused electron beam induced deposition (FEBID) processes, from electron scattering measurements.
MM and FFS acknowledge the Portuguese National Funding Agency FCT-MCTES through grants PD/BD/106038/2015 and researcher position IF-FCT IF/00380/2014, respectively, and together with PLV the research grant UID/FIS/00068/2013. KR acknowledges the Swiss National Science Foundation for an Early Postdoc Mobility fellowship. This work was also supported by Radiation Biology and Biophysics Doctoral Training Programme (RaBBiT, PD/00193/2012); UID/Multi/ 04378/ 2013 (UCIBIO). GG acknowledges partial financial support from the Spanish Ministerio de Economia, Industria y Competitividad (Project No. FIS2016-80440). CD thanks The Labex “Chimie des Systèmes Complexes” (ANR-10-LABX- 0026_CSC). The quantum chemical calculations have been performed on the computer nodes of the LCQS, Strasbourg and thanks to the computer facilities of the High Performance Computing (HPC) regional center of University of Strasbourg. The authors wish to acknowledge the beam time at the ASTRID2 synchrotron at ISA, Aarhus University, Denmark. We also acknowledge the financial support provided by the European Community's Seventh Framework Programme (FP7/ 2007-2013) CALIPSO under grant agreement number 312284. Some of this work forms part of the EU/ESF COST Action CELINA CM1301
11 pags., 4 figs., 2 tabs. -- This article is part of the Thematic Series "Chemistry for electron-induced nanofabrication".