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Photoionization and dissociation of anthracene, phenanthrene, and pentacene in the multiphoton regime at 266 nm wavelength were performed. (n = 4–6) ions were observed as fragments, and their yields as a function of laser intensity were studied. H-migration and “roaming” mechanisms leading to the formation of these fluxional ions from polycyclic aromatic hydrocarbons (PAHs) are proposed. The present results show higher photostability of PAHs with bent structure and suggest PAHs in the UV regions of interstellar medium as a prominent source for (n = 4–6).

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A low-lying resonance in FeCN− anion was identified through abrupt changes in the spectral dependence of the photoelectron angular distribution. Non-Franck–Condon transitions from the resonance to the neutral FeCN (4Δ), and the corresponding photoelectron angular distributions revealed that the resonance is a dipole scattering state. Significant thermionic electron emission was observed in the resonant photoelectron spectra, indicating a strong coupling of the resonance with the ground state of this triatomic anion and its competition over autodetachment. This low-lying resonance is identified to be an efficient pathway for the formation of FeCN− anion in the outer envelope of IRC+10216. The results in general reveal formation pathways in space for anions with low-lying resonances and large permanent dipole moment.

Nitrogen-bearing polycyclic aromatic hydrocarbons (PANHs) are ubiquitous in space. They are considered precursors to advanced biomolecules identified in meteorites. However, their chemical evolution into biomolecules in photodestructive astrophysical mediums remains a paradox. Here, we show that light can efficiently initiate the molecular mass growth of PANHs. Ultraviolet-photoexcited quinoline monomers, the smallest PANH, were observed to associate and intermolecular Coulombic decay between the associating monomers formed the cations of quinoline-dimer. Molecular rearrangements in the dimer cation lead to a dominant formation of cations heavier than quinoline. The enrichment of these heavier cations over all the other cations reveals the efficiency of this route for the mass growth of PANHs in space. This mechanism also leads to a highly reactive unsaturated PANH-ring via CH loss, a hitherto unknown channel in any photon-driven process. The occurrence of this efficient pathway toward complex molecules points to a rich chemistry in dense interstellar clouds.

In the present research an economically effective porous fly ash-based filter candle (FFC) was developed for the treatment of domestic wastewater using fly ash, sodium silicate, wood dust, silica fume and water. The four testing specimens of FFC having different sizes (10, 20, 30, and 40 mm) were prepared. The parameters such as turbidity, total suspended solids (TSS), dissolved oxygen (DO), total dissolved solids (TDS), and pH of domestic wastewater were studied before and after treatment. The test results showed that there is a decrease in values of turbidity from 7 to 5.9 NTU, TSS from 300 to 218 mg/L, TDS from 400 to 302 mg/L, pH from 10.6 to 7.9, and BOD from 9.5 to 7.9 while DO values decreased in the range of 8.9 to 7.7. The observed porosity, compressive strength, and flow rate of FFC fall in the range of 24.55-27.26 %, 1.5-2.3 MPa, and 180-290 ml/h, respectively. The filtration tests using FFC exhibited good performance with >92 % filtration efficiency. Overall results have shown that FFC having a 30 mm bed thickness is recommendable for effective wastewater treatment. Thus, an attempt has been made to introduce a novel technology for domestic wastewater treatment using industrial fly ash waste.