Photoionization study of the vinyl radical

Journal Article · Wed Jun 15 04:00:00 EDT 1988 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.454352· OSTI ID:5183071

Berkowitz, J; Mayhew, C A; Rus-hacekcic, B

The photoionization spectrum of vinyl radical is reported, from its observed threshold to 1160 A. Two methods of preparation have been employed; (a) the abstraction reaction of F atoms with C/sub 2/H/sub 4/, and (b) the pyrolysis of divinyl mercury at 1200 K. In both experiments, relatively sharp autoionization structure is observed, and interpreted as a Rydberg series converging to the excited /sup 3/A'' state of vinyl cation. The analysis leads to an adiabatic ionization energy of approx.10.7 eV for this state, with a structure similar to that of vinyl radical but with an increased C--C distance. The observed ionization threshold for the ground state of vinyl cation is 8.59 +- 0.03 eV with the F atom reaction, and 8.43 +- 0.03 eV with the pyrolysis method. The lower value in the latter experiment is interpreted as a hot band. The relatively low value of the photoionization cross section near threshold implies a large geometry change between vinyl radical and ground state vinyl cation. A progression in the in-plane C--H bending vibration is indicated in the photoionization spectrum; it is quite possible that the vibrational 0--0 transition lies one quantum lower than our detected limit. With this bracketed adiabatic ionization potential and the appearance potential of C/sub 2/H/sup +//sub 3/ (C/sub 2/H/sub 4/), a C--H bond energy in ethylene of 107--110 kcal/mol (0 K) is deduced.

• Research Organization: Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 5183071
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 88:12; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKENES
ALKYL RADICALS
BREMSSTRAHLUNG
CHEMICAL REACTIONS
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ELEMENTS
ETHYLENE
FLUORINE
HALOGENS
HYDROCARBONS
IONIZATION
IONIZATION POTENTIAL
MERCURY COMPOUNDS
NONMETALS
ORGANIC COMPOUNDS
ORGANIC MERCURY COMPOUNDS
PHOTOIONIZATION
PYROLYSIS
RADIATIONS
RADICALS
SPECTRA
SYNCHROTRON RADIATION
THERMOCHEMICAL PROCESSES
ULTRAVIOLET SPECTRA
VINYL RADICALS