P. Loffler et al., PHOTOFRAGMENT ACTION SPECTROSCOPY OF THE ACETYLENE MOLECULE IN THE VACUUM-ULTRAVIOLET, Chemical physics letters, 252(5-6), 1996, pp. 304-310
The photodissociation dynamics of acetylene to hydrogen atoms, C2H2 --
> C2H + H and C2D2 --> C2D + D, with C2H and C2D in the ground <(X)ove
r tilde (2) Sigma(+)> and/or excited electronic <(A)over tilde (2) Pi>
states, has been investigated for the first time with tunable narrow-
band vacuum ultraviolet laser radiation between 121 and 133 nm by empl
oying hydrogen atom photofragment action spectroscopy. Action spectra
have been taken at 2.5 cm(-1) resolution with acetylene in a molecular
beam adiabatically cooled internally to about 4 K. They exhibit prono
unced discrete predissociative resonances of Rydberg and valence excit
ed states resolved to homogeneous widths. From them dissociation lifet
imes of individual states from 5 x 10(-14) s to longer than 2 x 10(-12
) s are derived.