Abstract:
Impurity free eluission spectra of HCCCHO and DCCCHO have
been rephotographed using the electronic-energy-exchange method
with benzene as a carrier gas. The near ultraviolet spectra of
ReeCHO and DCCCHO were photographed in a sorption under conditions
of high resolution with absorption path lengths up to 100 meters.
The emission and absorption spectra of Propynal resulting from
3 n 1 t
1\ - A excitation has been reanalyzed in som.e detail. Botrl of
the eH out-of-plane wagging modes were found to have negative
anharmonicity. A barrier height of 56.8/0.0 cm- 1 and a nonplanar
oft , ,
equilibrium angle of 17 3 /30 are calculated for the V 10/ lJ 11
modes.
The in-plane and out-of-plane v1. brational modes in the 3A." and
1a~. ' elec ronic states of Propynal were subjected to a normal
coordinate treatment in the approximat :on of tIle Urey-Bradley
force field. From the relative oscillator strengths of the
trans1·t1·0ns connect i ng t he v ibrat1•0n1ess lA' , state and t,he V1· bron1·C
3· if
levels of the A state, the differences in equilibrium configuration
were evaluated from an approximate Franck-Condon analysis
based on the ground state normal coordinates. As this treatment
gave 512 possible geometrical structures for the upper state, it
4
was necessary to resort to a comparison of the observed and calculated
moments of inertia along with chemical intuition to isolate the structure.
A test of the correctness of the calculated structure change and the
vibrational assignment was raade by evaluating the intensities of the inplane
and out-oi-plane fundarnental, sequence, and cross sequellce transitions
y the exact Franck-Condon method.
