A. Fahr et al., ULTRAVIOLET-ABSORPTION AND CROSS-SECTIONS OF PROPARGYL (C3H3) RADICALS IN THE 230-300 NM REGION, Chemical physics, 215(1), 1997, pp. 59-66
The ultraviolet absorption spectrum and cross sections of propargyl (C
3H3) radicals have been, for the first time, determined in the gas pha
se in the spectral range of 230-300 nm. The propargyl radicals were pr
oduced from 193 nm excimer laser photolysis of C3H3Cl, 248 nm photolys
is of C3H3Br and from reaction of Cl-atoms with propargyl chloride. Th
e spectra obtained from the three systems were nearly identical. The u
ltraviolet spectrum for the propargyl radicals exhibits a relatively b
road absorption with a maximum cross section of 1.2 x 10(-17) cm(2) mo
lecule(-1) at 242 nm. The electronic transitions in propargyl radical
have also been calculated by ab initio quantum chemical methods at the
CASSCF, CASPT2, CIS, and EOM_CCSD levels of theory and assign the new
observed band to the in plane pi(b(2))<--pi(b(2)) allowed transition
. In addition, we report here the absorption spectra and cross section
s for propargyl chloride and propargyl bromide, precursors of propargy
l radicals, in the spectral range of 160-230 nm.