Studies of transition states and radicals by negative ion photodetachment

Technical Report · Sun Dec 01 04:00:00 EST 1991

DOI:https://doi.org/10.2172/7207001· OSTI ID:7207001

Metz, R B

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{sup {minus}} anion provides a direct spectroscopic probe of the transition state region of the potential energy surface for the neutral hydrogen transfer reaction X + HY {yields} 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 CH{sub 2}NO{sub 2} by photoelectron spectroscopy of CH{sub 2}NO{sub 2}{sup {minus}}, determining the electron affinity of CH{sub 2}NO{sub 2}, gaining insight on the bonding of the {sup 2}B{sub 1} ground state and observing the {sup 2}A{sub 2} 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 CH{sub 2}NO{sub 2} 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 Lab., CA (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 7207001
• Report Number(s): LBL-31878; ON: DE92017011
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ADIABATIC PROCESSES
ANIONS
CHARGED PARTICLES
COMPUTERIZED SIMULATION
ELECTRON SPECTROSCOPY
ENERGY
ENERGY LEVELS
EXCITED STATES
HALOGEN COMPOUNDS
HYDROGEN TRANSFER
IONS
NITRO COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
POTENTIAL ENERGY
RADICALS
REACTION INTERMEDIATES
SIMULATION
SPECTROSCOPY