Electronic spectroscopy of benzo[g,h,i]perylene and coronene inside helium nanodroplets

Abstract

We have recorded the electronic spectra of benzo[g,h,i]perylene and coronene and their van der Waals complexes with argon and oxygen with a helium-nanodroplet depletion spectrometer. These molecules differ by the addition of one and two fused benzene rings to perylene, which was previously studied in helium. The coronene spectrum is similar to a previously reported jet-cooled laser-induced fluorescence (LIF) spectrum. The van der Waals complexes with argon and oxygen show different complexation sites and maximum number of adsorbants. We report a vibronically resolved benzo[g,h,i]perylene S(1) <-- S(0) spectrum. The spectral lines are split in a similar way to that of several molecules studied before. However, surprisingly, while the van der Waals complexes with argon are free of the splitting, the complexes with oxygen retain the splitting, with increased linewidth and splitting. We could also observe the S(2) <-- S(0) origin transition of benzo[g,h,i]perylene which was previously observed by cavity ring down spectroscopy. While in general the two spectra are quite similar, the relative intensities and spectral shifts of several lines are different.

Comparative investigation of pure and mixed rare gas atoms on coronene molecules

“…In their electronic spectroscopy experiment on argoncoronene complexes inside He droplets, Birer et al [31] observed two redshifted peaks in the S 1 ← S 0 spectrum which were assigned to clusters where one Ar atom was localized on the outer rings or over the central hollow, respectively. A third peak appeared with increasing Ar pressure which was subsequentely attributed to the presence of two Ar atoms, although nothing could be stated regarding the precise position on the coronene plane.…”

“…The authors suggested in their analysis a possible competition between helium and argon atoms to occupy favourable docking sites on the molecular substrate. Redshifted peaks in the electronic spectra of argon-coronene clusters inside helium nanodroplets were interpreted in terms of the location of the Ar atoms in the spectroscopic study by Birer et al [31]. A similar investigation was performed recording the laser-induced fluorescence spectra of tetracene complexes in 4 He droplets with increasing pressures of Ne [50].…”

Theoretical study on tertiary amine-fluorophore photoinduced electron transfer (PET) systems

“…Experimental data [11,12] and other theoretical [11,13] where available are also included. As these systems attract attention on their own, experimental and theoretical studies on their spectroscopy as well as on substituted forms continue to appear [14]. The present work is focused on the transitions of relevance to the fluorescent sensor systems and the spectroscopy of the fluorophores, in general, is not considered here.…”

Absorption spectroscopy of adenine, 9-methyladenine, and 2-aminopurine in helium nanodroplets

“…For example, studies on benzo[g,h,i]perylene show that in a helium environment the S 2 band origin is significantly broadened. 73 This has been attributed to an enhanced S 2 -S 1 internal conversion in liquid helium. Even more striking are the effects on the photochemistry of 3-hydroxyflavone.…”