A molecular beam study of the H+N3 reaction. Product NH internal state distribution and electronic state branching ratio

1990 ◽  
Vol 93 (6) ◽  
pp. 4033-4042 ◽  
Author(s):  
Jing Chen ◽  
Edwin Quiñones ◽  
Paul J. Dagdigian
Keyword(s):  
Electronic State ◽  
Molecular Beam ◽  
Internal State ◽  
Branching Ratio ◽  
State Distribution

Fringe fields are important when examining molecular orientation in a cold ammonia beam

2021 ◽  
Author(s):  
Paul Bertier ◽  
Brianna Heazlewood
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Molecular Orientation ◽  
Molecular Beam ◽  
Buffer Gas ◽  
State Distribution ◽  
Experimental Apparatus ◽  
Set Up ◽  
A Minor ◽  
Fringe Fields

Abstract External fields have been widely adopted to control and manipulate the properties of gas-phase molecular species. In particular, electric fields have been shown to focus, filter and decelerate beams of polar molecules. While there are several well-established approaches for controlling the velocity and quantum-state distribution of reactant molecules, very few of these methods have examined the orientation of molecules in the resulting beam. Here we show that a buffer gas cell and three-bend electrostatic guide (coupled to a time-of-flight set-up) can be configured such that 70% of ammonia molecules in the cold molecular beam are oriented to an external electric field at the point of detection. With a minor alteration to the set-up, an approximately statistical distribution of molecular orientation is seen. These observations are explained by simulations of the electric field in the vicinity of the mesh separating the quadrupole guide and the repeller plate. The combined experimental apparatus therefore offers control over three key properties of a molecular beam: the rotational state distribution, the beam velocity, and the molecular orientation. Exerting this level of control over the properties of a molecular beam opens up exciting prospects for our ability to understand what role each parameter plays in reaction studies.

Crossed-beam studies of radical reaction dynamics:

1994 ◽  
Vol 72 (3) ◽  
pp. 660-672 ◽  
Author(s):  
R. Glen Macdonald ◽  
Kopin Liu Argonne ◽  
David M. Sonnenfroh ◽  
Di-Jia Liu
Keyword(s):  
Cross Sections ◽  
Molecular Beam ◽  
Radical Reaction ◽  
Reaction Cross ◽  
Translational Energy ◽  
Vibronic State ◽  
State Distribution ◽  
Title Reaction ◽  
Vibrational Ground State ◽  
Reaction Cross Sections

The title reaction has been studied in a crossed molecular beam apparatus. Both the product state distributions and the translational energy dependence of the reaction cross sections were measured under single collision conditions. Excellent agreement was found over a wide temperature range (26–3800 K) between rate constants deduced from the translational excitation function and recent thermal kinetic data. The rotational state distribution was found to be very cold compared to the reaction exothermicity, and could be described by a Boltzmann temperature of 110 K for all K-doublet levels. The vibronic state distribution was also found to be cold, with 70% of the products formed in the vibrational ground state. By comparing the molecular beam results for vibronic state distributions with those obtained from recent bulb experiments, it was conjectured that there appears to be a strong correlation between rotation in the reactants and bending excitation in the products.

DISSOCIATIVE CHEMISORPTION OF H2(D2) AT Fe(110)

1994 ◽  
Vol 01 (04) ◽  
pp. 693-696 ◽  
Author(s):  
A. WIGHT ◽  
A. HODGSON ◽  
G. WORTHY ◽  
D. BUTLER ◽  
B.E. HAYDEN
Keyword(s):  
Surface Temperature ◽  
Experimental Error ◽  
Internal State ◽  
Incident Angle ◽  
Translational Energy ◽  
Surface Site ◽  
Dissociative Chemisorption ◽  
State Distribution ◽  
Energy Scaling ◽  
Low Energies

The dissociative chemisorption of H2(D2) at a Fe(110) surface has been studied as a function of translational energy ET, internal energy Ei, incident angle θi, and surface temperature Ts. Adsorption is activated, the sticking probability increasing steadily with translational energy with no evidence of a threshold for dissociation. Within experimental error there is no isotope effect or surface temperature dependence (180 K<Ts<400 K). Using seeded beams at constant translational energy, sticking on a clean surface is insensitive to the internal state distribution of the incident molecules, consistent with a barrier to dissociative chemisorption in the entrance channel. For translational energies below 0.2 eV sticking deviates from normal energy scaling, momentum parallel to the surface strongly inhibiting dissociative chemisorption. Dissociaton is interpreted in terms of a localised surface site for dissociative chemisorption at low energies.

Internal‐state distribution of recombinative hydrogen desorption from Si(100)

1992 ◽  
Vol 96 (5) ◽  
pp. 3995-4006 ◽  
Author(s):  
Kurt W. Kolasinski ◽  
Stacey F. Shane ◽  
Richard N. Zare
Keyword(s):  
Internal State ◽  
Hydrogen Desorption ◽  
State Distribution
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