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Collisional quenching of excited vinylidene (/sup 3/B/sub 2/) radicals

Journal Article · · J. Phys. Chem.; (United States)
DOI:https://doi.org/10.1021/j100412a037· OSTI ID:5140225
;
Rate constants for the removal of excited-state vinylidene D/sub 2/CC (/sup 3/B/sub 2/) in the presence of He, Ar, N/sub 2/, H/sub 2/, CO, and CH/sub 4/ are reported at room temperature. The excited vinylidene radicals are generated via vacuum-ultraviolet photolysis of mixtures of C/sub 2/D/sub 3/Cl in the quencher gases through the reaction sequence C/sub 2/D/sub 3/Cl..-->..C/sub 2/D/sub 3/Cl*; C/sub 2/D/sub 3/Cl*..-->..D/sub 2/CC(/sup 3/B/sub 2/) + DCl. Excited triplet vinylidene radicals are then collisionally quenched to the singlet ground state which undergoes rapid isomerization to acetylene. Rate constant for removal of D/sub 2/C (/sup 3/B/sub 2/) by quenchers are determined by observation of the time-resolved absorption of either D/sub 2/CC(/sup 3/B/sub 2/) at 137 nm or product C/sub 2/D/sub 2/ at 151 nm. The observed quenching rate constants for the deuterated species are k/sub He/ = (1.9 +/- 0.3) x 10/sup -15/, k/sub Ar/ = (6.64 +/- 0.3) x 10/sup -15/, k/sub N/sub 2// = (8.5 +/- 0.2) x 10/sup -15/, k/sub H/sub 2// = (33.8 +/- 6.1) x 10/sup -15/, k/sub CO/ = (28.0 +/- 8.0) x 10/sup -15/, and k/sub CH/sub 4// = (28.0 +/- 8.0) x 10/sup -15/ cm/sup 3/ molecule/sup -1/ s/sup -1/. No evidence for chemical reaction could be observed. The derived quenching cross sections are correlated with the potential well depth model. This correlation is valuable in predicting nonreactive collisional cross sections for additional gases.
Research Organization:
National Bureau of Standards, Gaithersburg, MD
OSTI ID:
5140225
Journal Information:
J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 90:21; ISSN JPCHA
Country of Publication:
United States
Language:
English

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Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400302* -- Organic Chemistry-- Isotope Effects-- (-1987)
ALKANES
ARGON
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTION KINETICS
COLLISIONS
CROSS SECTIONS
DATA
DE-EXCITATION
DEUTERIUM COMPOUNDS
ELEMENTS
ENERGY LEVELS
ENERGY TRANSFER
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
EXPERIMENTAL DATA
FLUIDS
GASES
HELIUM
HYDROCARBONS
HYDROGEN
HYDROGEN COMPOUNDS
INFORMATION
KINETICS
MEDIUM TEMPERATURE
METHANE
MOLECULE COLLISIONS
MOLECULE-MOLECULE COLLISIONS
NITROGEN
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
RADIATIONLESS DECAY
RADICALS
RARE GASES
REACTION KINETICS
VINYLIDENE RADICALS