Ultraviolet photodissociation of C{sub 2}F{sub 5}I with a small and simple photofragment translational spectrometer

Journal Article · Tue Jul 28 00:00:00 EDT 2009 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.3186737· OSTI ID:21559751

Zijun, Yu; Xiling, Xu; Min, Cheng; Dan, Yu; Yikui, Du; Qihe, Zhu ^[1]

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1. National Laboratory of Molecular Sciences, State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

Photodissociation dynamics of C{sub 2}F{sub 5}I near 280 and 304 nm has been investigated on a small and simple time-of-flight photofragment translational spectrometer (PTS). On this new PTS, the photolyzed and ionized fragments, not accelerated by electric field, travel freely for a short flight path (<50 mm) and are detected by microchannel plates. In the spectra of the I*({sup 2}P{sub 1/2}) channel at 281.73 and 304.02 nm, vibrational peaks with spacing of {approx}350 cm{sup -1} are partially resolved, indicating the preferential excitation of CF{sub 2} wag mode ({nu}{sub 11}=366 cm{sup -1}) of C{sub 2}F{sub 5} photofragment. The fraction of the available energy disposed into the internal energy is higher than 50% for both I{sup *} channel and I channel, showing the high excitation of vibration in the C{sub 2}F{sub 5} fragments. The fragment recoil anisotropy parameter {beta}(I{sup *}), determined to be 1.70 at 281.73 nm and 1.64 at 304.02 nm, reveals that I* atoms are produced predominantly from the parallel {sup 3}Q{sub 0}<-N transition. The anisotropy parameter {beta}(I), determined to be 1.25 at 279.71 nm and 0.88 at 304.67 nm, implies that I atoms are produced from two excited states, i.e., direct dissociation via the perpendicular {sup 3}Q{sub 1}(leftarrow)N transition, and indirect dissociation via the parallel {sup 3}Q{sub 0}(leftarrow)N transition then curve crossing to the {sup 1}Q{sub 1} potential energy surface. Analysis on the recent studies with vibrational state resolution in the photodissociation of alkyl iodides in the A band reveals that the ''symmetric bending'' mode on {alpha}-carbon of alkyl iodides is the preferential vibrational excitation mode, which can be explained by the classic impulsive model.

• OSTI ID: 21559751
• Journal Information: Journal of Chemical Physics, Vol. 131, Issue 4; Other Information: DOI: 10.1063/1.3186737; (c) 2009 American Institute of Physics; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANISOTROPY
ATOMS
BENDING
CARBON
DISSOCIATION
ELECTRIC FIELDS
ENERGY TRANSFER
EXCITATION
EXCITED STATES
IODIDES
MICROCHANNEL ELECTRON MULTIPLIERS
ORGANIC COMPOUNDS
PEAKS
PHOTOLYSIS
PHOTON-MOLECULE COLLISIONS
POTENTIAL ENERGY
SPECTROMETERS
SURFACES
TIME-OF-FLIGHT METHOD
ULTRAVIOLET RADIATION
CHEMICAL REACTIONS
COLLISIONS
DECOMPOSITION
DEFORMATION
ELECTROMAGNETIC RADIATION
ELECTRON MULTIPLIERS
ELECTRON TUBES
ELEMENTS
ENERGY
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
HALIDES
HALOGEN COMPOUNDS
IODINE COMPOUNDS
MEASURING INSTRUMENTS
MOLECULE COLLISIONS
NONMETALS
PHOTOCHEMICAL REACTIONS
PHOTON COLLISIONS
RADIATIONS