Marcin Gronowski

Computational Chemistry


Posts Tagged ‘excited states’

Electronic absorption and phosphorescence of cyanodiacetylene

Electronic absorption and emission spectra have been investigated for cyanodiacetylene, HC5N, an astrophysically relevant molecule. The analysis of gas-phase absorption was assisted with the parallel rare gas matrix isolation experiments and with density functional theory (DFT) predictions concerning the excited electronic states. Mid-UV systems: B1Δ←X1Σ+  (origin at 282.5 nm) and B1Σ←X1Σ+ (306.8 nm) were observed. Vibronic assignments have been facilitated by the discovery of the visible phosphorescence a3Σ+←X1Σ+ in solid Ar, Kr, and Xe. Phosphorescence excitation spectra, as well as UV absorption measurements in rare gas matrices, revealed the enhancement of A←X transitions. The vibronic structure of dispersed phosphorescence spectra supplied new data concerning the ground state bending fundamentals of matrix-isolated HC5N. The experimental singlet-triplet splitting, 2.92 eV in Ar, closely matches the value of 3.0 eV predicted by DFT.

Full text: J. Chem. Phys. 133 (2010) 074310