Polycyclic aromatic hydrocarbons (PAHs) are regarded as key molecules in the astrochemical evolution of interstellar medium, but formation mechanism even their simplest prototype—naphthalene (C 10 H 8 )—has remained an open question. Here, we show a combined crossed beam and theoretical study that naphthalene can be formed gas phase via barrierless exoergic reaction between phenyl radical 6 5 ) vinylacetylene (CH 2 = CH-C ≡ CH) involving van-der-Waals complex submerged barrier entrance...

Polycyclic aromatic hydrocarbons and related species have been suggested to play a key role in the astrochemical evolution of interstellar medium, but formation mechanism even their simplest building block—the benzene molecule—has remained elusive for decades. Here we demonstrate crossed molecular beam experiments combined with electronic structure statistical calculations that (C 6 H ) can be synthesized via barrierless, exoergic reaction ethynyl radical 1,3-butadiene, C 2 + CCHCHCH → H,...

In this article, we first explored the chemical dynamics of simple diatomic radicals (dicarbon, methylidyne) utilizing crossed molecular beams method. This versatile experimental technique can be applied to study reactions relevant atmospheres planets and their moons as long intense stable supersonic beam sources reactant species exist. By focusing on dicarbon with hydrogen cyanide, untangled contribution in its singlet ground excited triplet states. These results were understand re-analyze...

Crossed molecular beams experiments on dicarbon molecules, C2(X1Σ+g/a3Πu), with unsaturated hydrocarbons acetylene (C2H2(X1Σ+g)), ethylene (C2H4(X1Ag)), methylacetylene (CH3CCH(X1A1)), and allene (H2CCCH2 (X1A1)) were carried out at 18 collision energies between 10.6 50.3 kJ mol−1 utilizing a universal crossed machine to untangle the reaction dynamics forming hydrogen deficient hydrocarbon radicals in circumstellar envelopes of carbons stars cold clouds. We find that all reactions proceed...

The aromatic indene molecule (C9H8) together with its acyclic isomers (phenylallene, 1-phenyl-1-propyne, and 3-phenyl-1-propyne) were formed via a “directed synthesis” in situ utilizing high-temperature chemical reactor under combustion-like conditions (300 Torr, 1200–1500 K) through the reactions of phenyl radical (C6H5) propyne (CH3CCH) allene (H2CCCH2). isomer distributions probed tunable vacuum ultraviolet (VUV) radiation from Advanced Light Source by recording photoionization efficiency...

We carried out the crossed molecular beam reaction of ground state methylidyne radicals, CH(X(2)Π), with acetylene, C(2)H(2)(X(1)Σ(g)(+)), at a nominal collision energy 16.8 kJ mol(-1). Under single conditions, we identified both atomic and hydrogen loss pathways forming C(3)H(2) C(3)H isomers, respectively. A detailed analysis experimental data suggested formation c-C(3)H(2) (31.5 ± 5.0%), HCCCH/H(2)CCC (59.5 l-HCCC (9.0 2.0%). The proceeded indirectly via complex involved unimolecular...

We present a joint crossed molecular beam and kinetics investigation combined with electronic structure statistical calculations on the reaction of ground-state cyano radical, CN(X2Σ+), 1,3-butadiene molecule, H2CCHCHCH2(X1Ag), its partially deuterated counterparts, H2CCDCDCH2(X1Ag) D2CCHCHCD2(X1Ag). The studies indicate that proceeds via long-lived C5H6N complex, yielding C5H5N isomer(s) plus atomic hydrogen under single collision conditions as nascent product(s). Experiments 1,3-butadienes...

Reactions of dicarbon molecules (C(2)) with C(4)H(6) isomers such as 1,3-butadiene represent a potential, but hitherto unnoticed, route to synthesize the first aromatic C(6) ring in hydrocarbon flames and interstellar medium where concentrations transient species are significant. Here, crossed molecular beams experiments their X(1)Sigma(g)(+) electronic ground state electronically excited a(3)Pi(u) have been conducted two partially deuterated counterparts (1,1,4,4-D4-1,3-butadiene...

The crossed beams reaction of ground state ethynyl radicals, C2H(X2Σ+), with allene, H2CCCH2(X1A1), was conducted under single collision conditions at a energy 22.0 ± 0.4 kJ mol−1. center-of-mass functions were combined earlier ab initio calculations and revealed that the barrier-less, proceeded via indirect dynamics through an addition radical to terminal carbon atom allene molecule, terminated by atomic hydrogen emission tight exit transition form ethynylallene product. overall found be...

The elementary reaction of the D1-ethynyl radical (C2D) with vinylacetylene (C4H4) was studied under single collision conditions via crossed molecular beam experiments and electronic structure calculations. results suggested that besides two acyclic isomers as predicted computationally, ortho-benzyne (o-C6H4)—in its singly deuterated form—which is considered an important intermediate in formation polycyclic aromatic hydrocarbons, can be formed this process. This carried out at a energy 40.9...

The crossed beam reactions of the methylidyne radical with ethylene (CH(X(2)Π) + C(2)H(4)(X(1)A(1g))), D4-ethylene C(2)D(4)(X(1)A(1g))), and D1-methylidyne (CD(X(2)Π) C(2)H(4)(X(1)A(1g))) were conducted at nominal collision energies 17-18 kJ mol(-1) to untangle chemical dynamics involved in formation distinct C(3)H(4) isomers methylacetylene (CH(3)CCH), allene (H(2)CCCH(2)), cyclopropene (c-C(3)H(4)) via C(3)H(5) intermediates. By tracing atomic hydrogen deuterium loss pathways, our...

We studied the reaction of phenyl radicals (C(6)H(5)) with propylene (C(3)H(6)) exploiting a high temperature chemical reactor under combustion-like conditions (300 Torr, 1200-1500 K). The products were probed in supersonic beam by utilizing tunable vacuum ultraviolet (VUV) radiation from Advanced Light Source and recording photoionization efficiency (PIE) curves at mass-to-charge ratios m/z = 118 (C(9)H(10)(+)) 104 (C(8)H(8)(+)). Our results suggest that methyl atomic hydrogen losses are...

We investigated the multichannel reaction of ground-state carbon atoms with acetylene, C2H2 (X1Σg+), to form linear and cyclic C3H isomers (atomic hydrogen elimination pathway) as well tricarbon plus molecular hydrogen. The experiments were conducted under single-collision conditions at three different collision energies between 8.0 kJ mol-1 31.0 mol-1. Our studies complemented by crossed beam isotopomers C2D2(X1Σg+), C2HD (X1Σ+), 13C2H2 (X1Σg+) clarify a potential intersystem crossing...

A hot topic! Crossed-molecular-beam experiments showed that phenylacetylene molecules—precursors to polycyclic aromatic hydrocarbons in combustion flames and carbon-rich planetary nebulae—can be formed through reactions of phenyl radicals with acetylene under single-collision conditions (see picture).

Crossed molecular beams experiments have been utilized to investigate the reaction dynamics between two closed shell species, i.e. reactions of tricarbon molecules, C3(X1Σg+), with allene (H2CCCH2; X1A1), and methylacetylene (CH3CCH; X1A1). Our investigations indicated that both these featured characteristic threshold energies 40–50 kJ mol−1. The are indirect suggested proceeded via an initial addition molecule unsaturated hydrocarbon molecules forming initially cyclic intermediates generic...

The reaction of ground-state ethynyl radicals, C(2)H(X(2)Sigma(+)), with d(4)-ethylene, C(2)D(4)(X(1)A(g)), was investigated at a collision energy 20.6 +/- 0.4 kJ mol(-1) utilizing the crossed-beams technique. Combined electronic structure calculations, our results elucidate that this follows indirect dynamics via doublet radical complex. is initiated by barrierless addition to carbon atom d(4)-ethylene molecule form C(4)HD(4) intermediate. latter long-lived compared its rotational period...

Various ablation sources generating supersonic boron monoxide (BO; X(2)Σ(+)) radical beams utilizing oxygen (O(2)), carbon dioxide (CO(2)), methanol (CH(3)OH), and water (H(2)O) as seeding gases were characterized in a crossed molecular setup by mass resolved time-of-flight spectroscopy spectroscopically via laser induced fluorescence. Intensities of the well rovibrational energy distributions analyzed. The source was found to produce excessive amount an unwanted BO(2) byproduct. Internal...

The combustion relevant elementary reaction of photolytically generated phenyl radicals (C(6)H(5), X(2)A(1)) with molecular oxygen to form the phenoxy radical (C(6)H(5)O) plus a ground state atom was investigated under single collision conditions at energy 21.2 ± 0.9 kJ mol(-1). found proceed indirectly via involvement long-lived phenylperoxy (C(6)H(5)O(2)) intermediate that decomposed rather loose exit transition state. In comparison crossed beams data obtained previously elevated energies,...

Crossed molecular beams experiments were conducted to investigate the chemical dynamics of reaction dicarbon molecules, C(2)(X(1)Sigma(g)(+)/a(3)Pi(u)), with diacetylene, C(4)H(2)(X(1)Sigma(g)(+)) at two collision energies 12.1 and 32.8 kJ mol(-1). The found be indirect, involved C(6)H(2) intermediates, dictated by an initial addition molecule carbon-carbon triple bond diacetylene. complexes could isomerize. On singlet surface, resulting linear triacetylene (C(6)H(2)(X(1)Sigma(g)(+)))...

Crossed molecular beam experiments were utilized to untangle the reaction dynamics form 1-phenylmethylacetylene [CH(3)CCC(6)H(5)] and 1-phenylallene [C(6)H(5)HCCCH(2)] in reactions of phenyl radicals with methylacetylene allene, respectively, over a range collision energies from 91.4 161.1 kJ mol(-1). Both proceed via indirect scattering are initiated by an addition radical terminal carbon atom allene reactants short-lived doublet C(9)H(9) complexes CH(3)CCHC(6)H(5) C(6)H(5)H(2)CCCH(2)....