Drift tube studies of ion-molecule reactions at high and at low temperatures

Thesis/Dissertation · Sun Dec 31 23:00:00 EST 1978

OSTI ID:5392277

Chen, A

A temperature variable drift tube-mass spectrometer apparatus has been used to determine the rate coefficients for the charge- and atom-transfer reactions O/sup +/ + N/sub 2/ and O/sup +/ + O/sub 2/ (from 300K to 900K), He/sup +/ + H/sub 2/ and He/sup +/ + D/sub 2/ (from 78 to approx. 300K), as well as for the association reactions R/sup +/ + 2R, where R is He, Ne, or Ar (from 78K to 300K). For the atom-transfer reaction O/sup +/ + N/sub 2/, the rate coefficient decreases from (1.2 +- 0.1) x 10/sup -12/ cm/sup 3//sec to 0.5 x 10/sup -12/ cm/sup 3//sec as the temperature is increased from 300K to 900K. For the charge-transfer reaction O/sup +/ + O/sub 2/, the rate coefficient decreases from (2.1 +- 0.2) x 10/sup -11/ cm/sup 3//sec at 300K to half this value as the temperature is raised to 700K. These results are in good agreement with heated flowing afterglow results. The bimolecular and thermolecular rate coefficients have been determined for the dissociative charge-transfer reactions He/sup +/ + H/sub 2/ and He/sup +/ + D/sub 2/. The two-body rate coefficient k(He/sup +/ + H/sub 2/) is (1.1 +- 0.1) x 10/sup -13/ cm/sup 3//sec at 330K and increases to 1.5 x 10/sup -13/ cm/sup 3//sec as the temperature is lowered to 78K. The three-body contribution K(He/sup +/ + 2H/sub 2/) increases from (4.4 +- 2.0) x 10/sup -31/ cm/sup 6//sec to 1.8 x 10/sup -30/ cm/sup 6//sec over the same temperature range. The corresponding two-body rate coefficients for He/sup +/ + D/sub 2/ are an order of magnitude smaller than those for H/sub 2/:k(He/sup +/ + D/sub 2/) = (1.1 +- 0.2) x 10/sup -14/ cm/sup 3//sec at 310K and (2.4 +- 0.8) x 10/sup -14/ cm/sup 3//sec at 78K, in qualitative agreement with recent theoretical predictions. The corresponding three-body rate coefficients for D/sub 2/ are on the same order as those of H/sub 2/:K(He/sup +/ + 2D/sub 2/) = (2.2 +- 0.7) x 10/sup -31/ cm/sup 6//sec and (2.1 +- 0.3) x 10/sup -30/ at 310K and 78K, respectively.

• Research Organization: Pittsburgh Univ., PA (USA)
• OSTI ID: 5392277
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ARGON
CHARGE EXCHANGE
CHARGED PARTICLES
COLLISIONS
DRIFT TUBES
ELEMENTS
FLUIDS
GASES
HELIUM IONS
HIGH TEMPERATURE
ION COLLISIONS
ION-MOLECULE COLLISIONS
IONS
LOW TEMPERATURE
MEDIUM TEMPERATURE
MOLECULE COLLISIONS
MOLECULES
NEON
NITROGEN
NONMETALS
OXYGEN
OXYGEN IONS
RARE GASES
TEMPERATURE DEPENDENCE