Differential cross sections for rotationally state-resolved inelastic scattering of HF by argon

Journal Article · Fri Mar 15 04:00:00 EST 1991 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.460654· OSTI ID:5699171

Rawluk, L J; Fan, Y B; Apelblat, Y; Keil, M ^[1]

---

1. Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada (CA)

We present differential cross section (DCS) measurements for scattering of HF by Ar. These crossed-beam experiments employ rotational state sensitivity, allowing determination of the DCS as a function of the scattered HF rotational state. The initial HF rotational distribution is generated by nozzle expansion, without further state selection. Its composition is mostly {ital J}=0 and {ital J}=1, with small admixtures for {ital J}{gt}1. The DCS for each final state {ital J}{prime} is measured using a stabilized cw HF chemical laser, in conjunction with a rotatable liquid He-cooled bolometer. Measurable signals are obtained for scattering into 0{le}{ital J}{prime}{le}5, where {ital J}{prime}=6 is the thermodynamic limit for our collision energy of 120 meV. The measured DCS's show a strong forward peak, largely from elastic scattering. In addition, the DCS's evolve from a broad shoulder in the {theta}{approx}25{degree}--40{degree} region for {ital J}{prime}=0---through a flattening of the wide-angle scattering for {ital J}{prime}=2 and {ital J}{prime}=3---to an increase in the scattering beyond {similar to}40{degree} for {ital J}{prime}=4. The DCS for scattering into {ital J}{prime}=5 also shows increased intensity at wide scattering angles, but its onset is delayed until {similar to}70{degree}. These features are shown to be independent of the laboratory {r arrow} center-of-mass kinematic transformation. The wide-angle scattering into {ital J}{prime}=4 and {ital J}{prime}=5 corresponds to transferring up to 40% and 60%, respectively, of the available kinetic energy into HF rotation. Since the center-of-mass scattering angles are up to {similar to}110{degree}, we interpret the observed features for {ital J}{prime}=4--5 in terms of rotational rainbow scattering from the hard core of the HF+Ar potential energy surface.

• OSTI ID: 5699171
• Journal Information: Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 94:6; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ARGON
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
BEAMS
COLLISIONS
CROSS SECTIONS
DIFFERENTIAL CROSS SECTIONS
ELEMENTS
ENERGY LEVELS
EXCITED STATES
FLUIDS
GASES
HYDROFLUORIC ACID
HYDROGEN COMPOUNDS
INORGANIC ACIDS
MOLECULAR BEAMS
MOLECULE COLLISIONS
NONMETALS
RARE GASES
ROTATIONAL STATES
VAN DER WAALS FORCES