Ultra-violet absorption spectrum of tetrachlorohylene
Abstract
Four banded absorption systems of the C2Cl4 molecule are described. The vibrational patterns of all four are almost identical, qualitatively and quantitatively; from which it is deduced that all four transitions are Rydberg in type. They belong to a Rydberg series converging to a first ionization potential at 9.33 eV. The vibrational patterns are due to excitation of the three fundamental vibrations, ν′1ν′2 and ν′3 of the upper states, and to be in accord with simple theory based on symmetry considerations. The qualitative conclusions are that, relative to the ground state of C2Cl4, the upper states (and the ground state of the C2Cl+4 ion) have an increased CC length, a less marked decrease in CCl length and a small increase in [graphic omitted] angle. These qualitative conclusions are then made quantitative by an application of the Franck-Condon principle; the increase in CC length is 0.11 ± 0.01 Å, the decrease in CCl length is 0.03 ± 0.015 Å and the increase in [graphic omitted] angle is 3 ± 1°.