PROPENSITIES TOWARD C2H((A)OVER-TILDE (2)PI) IN ACETYLENE PHOTODISSOCIATION

When expansion-cooled acetylene is excited to the v'(1)+3v'(3) vibrational level (4 quanta CH-stretch) and then photodissociated at 248.3 nm, the dominant product channel is C2H((A) over tilde(2) Pi). This differs markedly from one-photon 193.3 nm photodissociation, which provides 1200 cm(-1) less energy and yields C2H((X) over tilde(2) Sigma(+)) as the primary product. Photodissociation at 121.6 nm yields C2H((A) over tilde(2) Pi) exclusively. (C) 1995 American Institute of Physics.