Study of the reaction dynamics of Li+HF, HCl by the crossed molecular beams method

Journal Article · Mon Sep 15 00:00:00 EDT 1980 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.440453· OSTI ID:5050921

Becker, C H; Casavecchia, P; Tiedemann, P W; Valentini, J J; Lee, Y T

The reactions of (I) Li+HF..-->..LiF+H and (II) Li+HCl..-->..LiCl+H have been studied by the crossed molecular beams method. Angular distributions (N(THETA)) of product molecules have been measured at 4 collision energies (E/sub c/) ranging from about 2 to 9 kcal/mole and time-of-flight (TOF) measurements of product velocity distributions were made at approximately E/sub c/=3 and 9 kcal/mole for both reactions (I) and (II). The combined N(THETA) and TOF results were used to generate contour maps of lithium--halide product flux in angle and recoil velocity in the center-of-mass (c.m.) frame. For reaction (I) at E/sub c/=3 kcal/mole the c.m. angular distribution (T(theta)) shows evidence of complex formation with near forward--backward symmetry; slightly favored backward peaking is observed. The shape of this T(theta) indicates there is significant parallel or antiparallel spatial orientation of initial and final orbital angular momentum. It is deduced that coplanar reaction geometries are strongly favored. At E/sub c/=8.7 kcal/mole the T(theta) of reaction (I) becomes strongly forward peaked. The product translational energy distributions P(E/sub T/') at both these collision energies give an average E/sub T/'of approx.55% of the total available energy. The T(theta) at E/sub c/=2.9 and 9.2 kcal/mole for reaction (II) are forward--sideways peaked. Most of the available energy (approx.70%) goes into recoil velocity at both E/sub c/ for LiCl formation. Both reactions (I) and (II) show evidence of no more than a minor partitioning of energy into product vibrational excitation. Integral reactive cross sections (sigma/sub R/) are evaluated Values of sigma/sub R/ are: for LiF formation sigma/sub R/approx. =0.8 A/sup 2/ and 0.94 A/sup 2/ at E/sub c/=3 and 8.7 kcal/mole, while for LiCl formation sigma/sub R/= 27 A/sup 2/ and 42 A/sup 2/ at E/sub c/=2.9 and 9.2 kcal/mole.

• Research Organization: Materials and Molecular Research Division, Lawrence Berkeley Laboratory, Berkeley, California 94720
• OSTI ID: 5050921
• Journal Information: J. Chem. Phys.; (United States), Vol. 73:6
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
HYDROCHLORIC ACID
ATOM-MOLECULE COLLISIONS
HYDROFLUORIC ACID
LITHIUM
ANGULAR DISTRIBUTION
CHEMICAL REACTIONS
COLLIDING BEAMS
HYDROGEN
LITHIUM CHLORIDES
LITHIUM FLUORIDES
MOLECULAR BEAMS
ALKALI METAL COMPOUNDS
ALKALI METALS
ATOM COLLISIONS
BEAMS
CHLORIDES
CHLORINE COMPOUNDS
COLLISIONS
DISTRIBUTION
ELEMENTS
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
LITHIUM COMPOUNDS
LITHIUM HALIDES
METALS
MOLECULE COLLISIONS
NONMETALS
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena