✍ Scribed by K.H. Becker; R. König; R. Meuser; P. Wiesen; Kyle D. Bayes
No coin nor oath required. For personal study only.
The photolysis of carbon suboxide (C,O,) at 248 and 308 nm was investigated by monitoring laser-induced fluorescence (LIF) of the product C&0(X3x -). At 308 nm the C&O(X31; -) appears immediately after the photolysis flash followed by a slow decay. This clean source of C&O(X'Z -> was used to measure rate constants for reactions with O2 and CO and to set an upper limit on its reactivity with C02_ Measurements were also made of rate constants for the quenching of C;O(A"Q) by N2, SF,, CO and C02. At 248 nm the LIF signal starts at a small value and increases for several hundred microseconds before decaying. Both the maximum intensity of the LIF signal and its rate of rise can be increased by adding CO. It is concluded that photolysis at 248 nm initially forms one of the low-lying singlet states of C&O, probably a'b, and that most of this singlet state is lost by reaction with C,O,. CO has the unique ability to convert the singlet state of GO to the X%-state by intersystem crossing on the attractive C,O, surface. A semiquantitative model for this system has been proposed and its agreement with the experimental results is discussed. 1. Introduction Early work on the photolysis of carbon suboxide (G02) suggested that C&O is formed in the initial step [l-4]: ~0,+hv-+ c;o+co This C;O reacted with olefins to form primarily the corresponding allene. At photolysis wavelengths ,4 > 290 nm O2 inhibited the GO-olefin reaction, but for A < 255 nm the GO reacted with olefins even in the presence of 0 2_ On the basis of this chemical behaviour and simple molecular orbital arguments, it was proposed that GO had a 3IZ ground state and low-lying 'A and % states 131. Subsequent ab in&o calculations [5, 63 supported these assignments. The lowest singlet state is predicted to lie 0.74-0.95 eV above the ground triplet state. Devillers [7] and Devillers and Ramsay [8] first observed the A'II+ X3X-band system of GO in absorption following flash photolysis of GO,.
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## Abstract The photolysis was investigated at 313 nm wavelength, 253–529 K temperatures, and 4 × 10^−11^‐2 × 10^−9^ mol·photon/cm^2^·sec light intensities by determining the quantum yields of 20 reaction products. Primary quantum yields for the seven primary processes and rate constant ratios, rat