Optical spectroscopic study of tetracene guest site configurations in perdeuterated and partially deuterated p-terphenyl host crystals Original Research Article

The nature of the stable guest sites, O1 and O2, and the conformational relaxations in the host cage of the metastable sites, O3 and O4, of tetracene in partially deuterated and perdeuterated p-terphenyl crystals are investigated using stationary optical spectroscopy. Deuteration of the p-terphenyl host matrix leads to blue-shift the electronic origins of the guest spectra and a decrease of the splitting between the spectral lines of the O1 and O2 sites. The phonon sidebands in the excitation spectra of the metastable O3 and O4 sites in perdeuterated p-terphenyl were found to have a significantly smaller width as compared to that of the perprotonated host. This difference is shown to reflect the relatively smaller conformational changes of the perdeuterated host molecules surrounding the guests in the O3 and O4 sites.