I{sub 2} molecular elimination in single-photon dissociation of CH{sub 2}I{sub 2} at 248 nm by using cavity ring-down absorption spectroscopy

Journal Article · Fri Jan 21 00:00:00 EST 2011 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.3523571· OSTI ID:21559984

Chen, Shun-Yi; Tsai, Po-Yu; Lin, Hsiang-Chin; Wu, Chia-Ching; Lin, King-Chuen ^[1]; Sun, B J; Chang, A H. H. ^[2]

---

1. Department of Chemistry, National Taiwan University, Taipei, and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China)
2. Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan (China)

Following single-photon dissociation of CH{sub 2}I{sub 2} at 248 nm, I{sub 2} molecular elimination is detected by using cavity ring-down absorption spectroscopy. The technique comprises two laser beams propagating in a perpendicular configuration, in which a tunable laser beam along the axis of the ring-down cell probes the I{sub 2} fragment in the B {sup 3}{Pi}{sub ou}{sup +}- X {sup 1}{Sigma}{sub g}{sup +} transition. The nascent vibrational populations for v = 0, 1, and 2 levels are obtained with a population ratio of 1:(0.65 {+-} 0.10):(0.30 {+-} 0.05), corresponding to a Boltzmann-like vibrational temperature of 544 {+-} 73 K. The quantum yield of the ground state I{sub 2} elimination reaction is determined to be 0.0040 {+-} 0.0025. With the aid of ab initio potential energy calculations, the pathway of molecular elimination is proposed on the energetic ground state CH{sub 2}I{sub 2} via internal conversion, followed by asynchronous three-center dissociation. A positive temperature effect supports the proposed mechanism.

• OSTI ID: 21559984
• Journal Information: Journal of Chemical Physics, Vol. 134, Issue 3; Other Information: DOI: 10.1063/1.3523571; (c) 2011 American Institute of Physics; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ABSORPTION SPECTROSCOPY
BEAMS
CONFIGURATION
DISSOCIATION
GROUND STATES
INTERNAL CONVERSION
IODINE
LASERS
ORGANIC COMPOUNDS
PHOTOCHEMISTRY
PHOTOLYSIS
PHOTONS
POTENTIAL ENERGY
PROBES
SURFACES
TEMPERATURE DEPENDENCE
YIELDS
BOSONS
CHEMICAL REACTIONS
CHEMISTRY
CONVERSION
DECAY
DECOMPOSITION
ELEMENTARY PARTICLES
ELEMENTS
ENERGY
ENERGY LEVELS
HALOGENS
MASSLESS PARTICLES
NONMETALS
NUCLEAR DECAY
PHOTOCHEMICAL REACTIONS
SPECTROSCOPY