Studies of transition states and radicals by negative ion photodetachment

Thesis/Dissertation · Sun Dec 01 00:00:00 EST 1991

DOI:https://doi.org/10.2172/10158344· OSTI ID:10158344

Metz, Ricardo Baer ^[1]

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1. Univ. of California, Berkeley, CA (United States)

Negative ion photodetachment is a versatile tool for the production and study of transient neutral species such as reaction intermediates and free radicals. Photodetachment of the stable XHY^- anion provides a direct spectroscopic probe of the transition state region of the potential energy surface for the neutral hydrogen transfer reaction X + HY → XH + Y, where X and Y are halogen atoms. The technique is especially sensitive to resonances, which occur at a specific energy, but the spectra also show features due to direct scattering. We have used collinear adiabatic simulations of the photoelectron spectra to evaluate trail potential energy surfaces for the biomolecular reactions and have extended the adiabatic approach to three dimensions and used it to evaluate empirical potential energy surfaces for the I + Hl and Br + HI reactions. In addition, we have derived an empirical, collinear potential energy surface for the Br + HBr reaction that reproduces our experimental results and have extended this surface to three dimensions. Photodetachment of a negative ion can be also used to study neutral free radicals. We have studied the vibrational and electronic spectroscopy of CH₂NO₂ by photoelectron spectroscopy of CH₂NO₂^-, determining the electron affinity of CH₂NO₂, gaining insight on the bonding of the ²B₁ ground state and observing the ²A₂ excited state for the first time. Negative ion photodetachment also provides a novel and versatile source of mass-selected, jet-cooled free radicals. We have studied the photodissociation of CH₂NO₂ at 270, 235, and 208 nm, obtaining information on the dissociation products by measuring the kinetic energy release in the photodissociation.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 10158344
• Report Number(s): LBL-31878; ON: DE92017011
• Resource Relation: Other Information: TH: Thesis (Ph.D.); PBD: Dec 1991
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANIONS
PHOTOELECTRON SPECTROSCOPY
ADIABATIC PROCESSES
COMPUTERIZED SIMULATION
RADICALS
REACTION INTERMEDIATES
HYDROGEN TRANSFER
POTENTIAL ENERGY
EXCITED STATES
HALOGEN COMPOUNDS
NITRO COMPOUNDS
400201
CHEMICAL AND PHYSICOCHEMICAL PROPERTIES