Photofragmentation dynamics of iodohaloethanes

Technical Report · Fri Aug 01 04:00:00 EDT 1986

OSTI ID:7128953

Minton, T K

Detailed investigations are provided into the photofragmentation dynamics of two iodohaloethanes, CH/sub 2/ClCH/sub 2/I and CF/sub 2/BrCH/sub 2/I, thus illustrating the methodology of these studies. The results for these molecules along with five other similar systems are summarized and some trends that have become manifest are discussed. The center-of-mass translational energy distributions of the photofragments have been derived for both the I(/sup 2/P/sub 1/2/) and I(/sup 2/P/sub 3/2/) dissociation channels, yielding the relative probability for each channel (which varies widely as a function of the excitation wavelength and the substituents on the iodoethane). Angular distributions of the photofragments with respect to the laser polarization indicate that primary (C-I) photodissociation proceeds via a parallel transition (i.e., the transition moment must be nearly parallel to the C-I bond) for every system studied. Finally, the energy threshold for spontaneous secondary dissociation was observed for a number of systems, enabling the determination of the reaction enthalpy for RXI ..-->.. R + X + I, from which the heat of formation ..delta..H/sub f//sup 0/(0) of the iodohaloethane parent can be calculated and the stability of the haloethyl radical can be inferred.

• Research Organization: California Univ., Berkeley (USA). Dept. of Chemistry
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 7128953
• Report Number(s): LBL-22100; ON: DE87001725
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
400500* -- Photochemistry
ANISOTROPY
CHEMICAL REACTIONS
DISSOCIATION
ENERGY LEVELS
ENERGY SPECTRA
ENTHALPY
EXCITED STATES
FORMATION HEAT
FRAGMENTATION
HALOGENATED ALIPHATIC HYDROCARBONS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORIENTATION
PHOTOCHEMICAL REACTIONS
PHYSICAL PROPERTIES
REACTION HEAT
SPECTRA
SPIN ORIENTATION
THERMODYNAMIC PROPERTIES
TIME-OF-FLIGHT METHOD
WAVELENGTHS