Abstract
Absorption spectra of a long‐lived transient in the 140 and 157 nm region have been observed as the result of direct excitation of C2H2. The strongest features also are seen as the result of CH2CO photolysis. The carrier is identified as C2H2. A possible alternate assignment of the transient carrier to a geometrical isomer, such as H2C=C (vinylidene) radical is discussed.