Partial wave resonances predicted to occur in bimolecular collision processes have proven challenging observe experimentally. Here, we report crossed-beam experiments and quantum-scattering calculations on inelastic collisions between ground-state O2 H2 molecules that provide state-to-state cross sections for rotational excitation of (rotational state N = 1, j 0) (N 1) the vicinity thermodynamic threshold at 3.96 centimeter(-1). The close agreement experimental theoretical results confirms...

We report combined studies on the prototypical S(1D2) + H2 insertion reaction. Kinetics and crossed-beam experiments are performed in experimental conditions approaching cold energy regime, yielding absolute rate coefficients down to 5.8 K relative integral cross sections collision energies as low 0.68 meV. They supported by quantum calculations a potential surface treating long-range interactions accurately. All results consistent excitation function behavior is explained terms of...

We report on crossed-beam experiments and quantum-mechanical calculations performed the CO(j=0) + H2(j=0) → CO(j=1) system. The experimental cross sections determined in threshold region of CO(j=0 j=1) transition at 3.85 cm(-1) show resonance structures good qualitative agreement with theoretical ones. These results suggest that potential energy surface which describes CO-H2 van der Waals interaction should be reinvestigated for quantitative agreement.

Many chemical models of dense interstellar clouds predict that the majority gas-phase elemental nitrogen should be present as N(2), with an abundance approximately five orders magnitude less than hydrogen. As a homonuclear diatomic molecule, N(2) is difficult to detect spectroscopically through infrared or millimeter-wavelength transitions. Therefore, its often inferred indirectly reaction product N(2)H(+). Two main formation mechanisms, each involving two radical-radical reactions, are...

The temperature dependences of the methylidyne radical reactions with methane, allene, methylacetylene and propene were studied. This work was carried out in a supersonic flow reactor coupled pulsed laser photolysis (PLP) laser-induced fluorescence (LIF) techniques. Three Laval nozzles designed to provide uniform expansions nitrogen at Mach 2 argon 3 reach low temperatures, e.g. 170, 128 77 K, respectively. CH radicals produced by PLP CHBr3 266 nm probed LIF. exponential decays acquired,...

More than 100 reactions between stable molecules and free radicals have been shown to remain rapid at low temperatures. In contrast, two unstable received much less attention due the added complexity of producing measuring excess radical concentrations. We performed kinetic experiments on barrierless N((4)S) + OH((2)Π) → H((2)S) NO((2)Π) reaction in a supersonic flow (Laval nozzle) reactor. used microwave-discharge method generate atomic nitrogen relative-rate follow kinetics. The measured...

The temperature dependence of the reactions dicarbon molecule in its ground singlet (X 1Σ+g) and first excited triplet (a 3Πu) states with acetylene, methylacetylene, allene propene has been studied using a recently constructed continuous supersonic flow reactor. Four Laval nozzles have designed to access specified temperatures over range 77 ≤ T 220 K measurements performed at 296 under subsonic conditions. C2 was produced two lowest electronic via situ multiphoton dissociation C2Br4 266 nm....

AbstractWe review the experimental findings on scattering resonances in molecular collisions occurring energy domain equivalent to temperatures of a few Kelvin. We discuss conditions required observe shape (or orbiting) and Feshbach resonances, crucial factor being all cases number partial waves involved process. This implies operating with supersonic beams matched low velocities, high velocity resolution beam-intersection angle. is exemplified for elastic, inelastic reactive collisions,...

The fast reaction between C(3P) and C2H2 is thought to be an important process in dense interstellar clouds as it provides a mechanism for the growth of carbon chains. This feature article describes complementary series recent experimental theoretical investigations on this reaction. includes kinetic measurements rate constants at low temperatures crossed molecular beam determinations integral differential cross sections. theory employs first-principles electronic structure computations wave...

The reactive collisions of aluminium atoms with O2, CO2 and SO2 have been studied crossed pulsed supersonic molecular beams. Aluminium were obtained from vaporization an rod, using excimer laser. They probed, together the product AlO, by laser-induced fluorescence. Collision energy ranges 0.08–0.49 eV for Al + 0.14–0.53 0.30–1.19 SO2. variation AlO rovibrational distributions cross-sections collision has determined each reaction. value D0°(AlO)= 5.26 ± 0.03 found dissociation energy.

Reactions of the hydroxyl radical with propene and 1-butene are studied experimentally in gas phase a continuous supersonic flow reactor over range 50≤T/K≤224. OH radicals produced by pulsed laser photolysis H(2)O(2) at 266 nm followed laser-induced fluorescence (1, 0) A(2)Σ(+)←X(2)Π(3/2) band about 282 nm. These reactions found to exhibit negative temperature dependences entire investigated, varying between (3.1-19.2) (4.2-28.6)×10(-11) cm(3) molecule(-1) s(-1) for 1-butene, respectively....

We report integral cross sections for the S(1D2)+HD(j=0)→DS+H and HS+D reaction channels obtained through crossed-beam experiments reaching collision energies as low 0.46 meV from adiabatic time-independent quantum-mechanical calculations. While good overall agreement with experiment at above 10 is observed, neither product channel branching ratio nor low-energy resonancelike features in can be theoretically reproduced. A nonadiabatic treatment employing highly accurate singlet triplet...

Carbon monoxide is one of the most abundant components in many interstellar media and modeling its spectra requires knowledge rate coefficients for rotational (de-)excitation by collision with dominant species molecular regions, H2. In this Letter, we report on experimental observation resonances collisional excitation CO para- ortho-H2 at low energies characteristic cold clouds (down to a few Kelvin). Our integral cross sections are compared results new quantum mechanical scattering...

The kinetics of the N(4S°) + NO(X2Π) reaction have been studied in a continuous supersonic flow reactor over range 48 K ≤T≤ 211 K. Nitrogen atoms were produced by microwave discharge upstream Laval nozzle and probed vacuum ultraviolet resonance fluorescence. has found to exhibit small negative temperature dependence, with rate coefficient decreasing from (5.8 ± 0.3) × 10−11 cm3 molecule−1 s−1 at (3.3 0.2) statistical uncertainties cited level single standard deviation mean.

Rate constants for the potentially important interstellar N(4S) + CH(X2Πr) reaction have been measured in a continuous supersonic flow reactor over range 56 K ≤ T 296 using relative rate technique employing both OH(X2Πi) and CN(X2Σ+) reactions as references. Excess concentrations of atomic nitrogen were produced by microwave discharge method upstream Laval nozzle CH OH radicals created situ pulsed laser photolysis suitable precursor molecules. In parallel, quantum dynamics calculations title...

We report the results of two sets experiments on each reactions and

The integral cross section of the S((1)D(2)) + H(2)(j = 0) → SH H reaction has been measured for first time at collision energies from 0.820 down to 0.078 kJ mol(-1) in a high-resolution crossed beam experiment. excitation function obtained exhibits non-monotonic variation with energy and compares well results high-level quantum calculations. In particular, structures observed lower part, where only few partial waves contribute, can be described terms sequential opening individual channels,...

The dynamics of the C + C2H2 reaction has been investigated using two crossed molecular beam apparatus different concepts. Differential cross sections have obtained for C(3PJ) C2H2(X1sigmag+) --> l/c-C3H H(2S1/2) in experiments conducted with pulsed supersonic beams and variable crossing angle configuration at relative translational energies ET = 0.80 3.5 kJ mol(-1). atoms were detected by time-of-flight mass spectrometry sequential excitation to 2PJ(o) state a laser tuned Lyman-alpha...

Context. Oxygen molecules (O2) are of particular interest because their crucial role in astrochemisty. Modelling O2 molecular emission spectra from interstellar clouds requires the calculation rate coefficients for excitation by collisions with most abundant species.