Determination of absolute photoionization cross‐sections of some aromatic hydrocarbons

Abstract

Rationale: Aromatic hydrocarbons play an important role in the formation and growth of polycyclic aromatic hydrocarbon (PAH) and soot particles. Measurements of their absolute photoionization cross-sections (PICSs), that benefit the quantitative investigation of mass spectrometry, are still lacking, however. Methods: PICSs of some aromatic hydrocarbons were measured with tunable synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). Nitric oxide and benzene were chosen as standard references for PICS calibration, since their photoionization cross-sections are well documented in the literature. Binary liquid mixtures of the investigated molecules and their specific solvents were used in the measurements. Results: The investigated aromatics include naphthalene, phenanthrene, 1-methylnaphthalene, indene, 2-/3-/4-methylphenylacetylene, 2-methylindene, diphenylacetylene, 1-/2-ethynylnaphthalene and acenaphthylene. Photo-induced fragments from the molecules were also observed with increasing photon energy. Conclusions: Based on our measurements and literature data, PICSs of most aromatic molecules have very similar values beyond their ionization energies. However, molecules that contain the phenylacetylene structure have PICSs higher than other aromatics.

Inception of Carbonaceous Nanostructures via Hydrogen-Abstraction Phenylacetylene-Addition Mechanism

“…1-Naphthyl and 4-phenanthryl, respectively, add to phenylacetylene and subsequently eliminate the phenyl radical, which then transforms to benzene ( m / z = 78, C 6 H 6 ). As shown in Figure A,C,G, PIE curves of m / z = 78, 152, and 202 measured in the reactions agree with the reference curves of benzene, acenaphthylene, and pyrene, respectively (Supporting Information). Altogether, the experiments illustrate that phenyl-acenaphthylene and acenaphthylene are formed in the 1-naphthyl/phenylacetylene reaction, while 4-phenyl-pyrene and pyrene are formed in the 4-phenanthryl/phenylacetylene reaction.…”

“…These results suggest a C 14 H 10 byproduct other than 4-phenanthryl-derived phenanthrene in these reaction systems. The PIE curve of m/z = 178 in Figure 4D perfectly agrees with the reference curve of diphenylacetylene, 42 and the PIE curve in Figure 4F is fit by a linear combination of the reference curves of diphenylacetylene and phenanthrene (evaluated branching ratios: 74% and 26%, respectively). Because of the formation of phenyl radical in the reaction systems of 1-naphthyl/phenylacetylene and 4phenanthryl/phenylacetylene, the mass peak m/z = 178 (C 14 H 10 ) may be diphenylacetylene formed via the combination of phenyl and phenylacetylene.…”

Insights into a Low-Rank Naomaohu Coal Structural Information by Multistage Fractions Coupled with LIAD-VUVPI-TOFMS

“…It is worth noting that the absolute photoionization cross sections of naphthalene, phenanthene, and pyrene are roughly the same at 9.8 eV. 33 The LIAD process is the main cause of relative intensity gap. Similar phenomena also occur in other types of mixtures ( Figure 3 a–d).…”

Combined experimental and theoretical study on photoionization cross sections of benzonitrile and o/m/p-cyanotoluene

“…fitting their new experiments on some aromatic hydrocarbons . 27 The photoionization cross-sections rises smoothly in the FC region since the geometric configuration of the ionization state and the neutral state does and multi-channel FCHF (including contributions from HOMO-1 to HOMO- 7) approximations, respectively. The ionization energy of deep orbitals was taken from the photoelectron spectr um measured by Palmer et al 40 We also simulated the photoelectron spectrum shown in Figure 2 Figure 3 shows the measured and calculated photoionization crosssections of o/m/p-cyanotoluene.…”

“…Zhou et al 26 determined the absolute photoionization crosssections of some aromatics and aromatic derivatives, helping quantitative analysis of combustion intermediates. Recently, Jin et al 27 added the photoionization cross-sections of 12 aromatic hydrocarbons using tunable SVUV-PIMS. Comparing with the abundant data reported for aromatic hydrocarbons, the photoionization cross-sections of nitrogen-containing aromatic compounds are very scarce.…”