Photolysis of adsorbed benzene at 248 nm

Experimental Simulation of Titan's Stratospheric Photochemistry: Benzene (C6H6) Ices

“…Figure 6 compares the subtraction infrared spectrum at 70 K of the benzene ice (case 1) after-before UV photolysis with the infrared spectrum of amorphous benzene ice (50 K). The peaks marked with asterisks, on the left side of the figure, correspond to amorphous benzene features while the ones, marked with triangles, on the right side, are characteristic of the formation of polymeric material, as has already been highlighted by Couturier-Tamburelli et al (2015, 2018, in the case of HC 5 N or HC 3 N photolysis.…”

“…The photolysis of adsorbed benzene at 105 K under KrF laser (λ = 248 nm) has demonstrated several dissociative pathways; absorption of one or two 248 nm photons induces the breaking of the CH bond causing the release of H° and C 6 H 5 • , only three-photon excitation triggers the aromatic ring opening, allowing the detection of C 2 H 4 and C 2 H 2 fragments by mass spectrometry (Varakin, 2018) • and H° fragments, also produced at shorter wavelengths (λ = 193 nm), lead to the formation of aerosols.…”

The Photolysis of Aromatic Hydrocarbons Adsorbed on the Surfaces of Cosmic Dust Grains

“…We based our study on the results of experiments on laser-induced dissociation of adsorbed molecules carried out in the Laser Chemistry Group of the Chemistry Department of Moscow State University [20]. A single-layer coating of benzene molecules on a surface of fused quartz cooled with liquid nitrogen to a temperature of ∼ 100 K was deposited at a pressure of 2 × 10 −5 Pa over a time of 10 s. The substrate with the physically adsorbed benzene molecules was irradiated by a pulse of radiation from a KrF excimer laser (wavelength λ = 248 nm, pulse duration ∆t l = 20 ns) with an energy density F l that was varied from 20 to 120 mJ cm −2 .…”

“…Dissociation will be more efficient if the excitation of the adsorbed benzene molecules in the vibronic quasicontinuum occurs not as a result of a two-photon process involving UV photons, but instead via a resonance absorption of a single VUV photon. The dissociation of adsorbed molecules by the KrF laser described in [20] supposes the absorption of two photons to bring a molecule to the quasicontinuum and the stimulated emission of a third photon to bring about a transition to a dissociative state. When the molecule makes a transition between levels i − 1 and i after the absorption of the ith photon (i = 1, 2, 3), the kinetic equation for populating the level N i can be written…”

“…In our current study, we have considered another factor influencing the photostability of a number of adsorbed molecules. A series of laboratory experiments on the photostability of adsorbed molecules of the simplest aromatic hydrocarbons, such as benzene [20], chlorobenzene [21], and toluene [22] have been carried out in the Chemistry Department of Moscow State University using powerful UV laser radiation. It was established in these experiments that adsorbed molecules are much more stable than their gas-phase analogs, due to the transfer of the excess internal energy of the photoexcited molecule to the substrate via rapid intramolecular relaxation.…”