Molecular-beam scattering

Abstract

The molecular beam technique has been used in three different experimental arrangements to study a wide range of inter-atomic and molecular forces.

Directed Gas-Phase Formation of Aminosilylene (HSiNH2;X1A′): The Simplest Silicon Analogue of an Aminocarbene, under Single-Collision Conditions

“…To elucidate the nature of the SiND 3 and SiNDH 2 isomers formed via the atomic deuterium and hydrogen losses, respectively, the laboratory data were transformed into a CM reference frame. This procedure yields two distributions, i.e., the CM translational energy P ( E T ) and angular T ( θ ) flux distribution. , In both systems, the laboratory data could be fit with a single channel, i.e., D loss channel (SiND 3 (48 amu) plus D (2 amu); reaction ) and H loss channel (SiNDH 2 (46 amu) plus H (1 amu); reaction ) (Figure ). In detail, for products formed without internal excitation, considering the law of energy conservation, the maximum translational energy ( E max ) of 14 ± 6 kJ mol –1 and 18 ± 6 kJ mol –1 , which can be derived from the P ( E T ), represents the sum of the reaction exoergicity and the collision energy (15.9 ± 0.4 kJ mol –1 ; 14.9 ± 0.4 kJ mol –1 ).…”

Untangling the reaction dynamics of the silylidyne radical (SiH; X2Π) with acetylene (C2H2; X1Σg+)

“…collecting the arrival time of the ionized products for distinct massto-charge ratios (m/z) at different scattering angles in the laboratory reference frame. The TOF spectra and the laboratory angular distribution were further analysed using a forwardconvolution fitting routine[29,30]. This routine starts with a parameterized set of translational energy flux distribution (P(E T )) and angular flux distribution (T(θ)) in the center-of mass (CM) frame; these functions are then iteratively modified until the best fits of the TOF spectra and angular distribution are reached.…”

A chemical dynamics study on the gas phase formation of thioformaldehyde (H2CS) and its thiohydroxycarbene isomer (HCSH)

“…The analysis of the raw data revealed compelling evidence that, for the reaction of ground-state methylidyne radicals with hydrogen sulfide, a molecule with the chemical formulae H 2 CS is formed via atomic hydrogen elimination, with the hydrogen originating predominantly from the hydrogen sulfide reactant. To gain information on the underlying reaction dynamics, we transformed the experimental data from the laboratory to the CM reference frame (26,27); this process yielded the CM translational energy-flux distribution P(E T ) and the CM angular-flux distribution T(θ) (Fig. 3).…”

“…The rotatable detector within the plan of both reactant beams allowing the collection of up to 2 × 10 6 TOF angular-resolved TOF spectra at discrete angles, integrated and normalized them with respect to the intensity at the CM angle yield the laboratory angular distribution. In order to obtain information on scattering dynamics, a forward-convolution routine was employed to convert the laboratory-frame data into the CM frame (26,27). Considering the reaction has no entrance barrier, a reactive scattering cross-section of an E T -1/3 energy dependence with E T defining the translational energy within the line-of-center model for entrance barrierless, exoergic reactions was exploited.…”