TY - JOUR
T1 - Vibrationally mediated photodissociation of ethylene cation by reflectron multimass velocity map imaging
AU - Kim, Myung Hwa
AU - Leskiw, Brian D.
AU - Suits, Arthur G.
PY - 2005/9/8
Y1 - 2005/9/8
N2 - A new imaging technique, reflection multimass velocity map ion imaging, is used to study the vibrationally mediated photodissociation dynamics in the ethylene cation. The cation ground electronic state is prepared in specific vibrational levels by two-photon resonant, three-photon ionization via vibronic bands of (π, nf) Rydberg states in the vicinity of the ionization potential of ethylene, then photodissociated through the (B̃ 2A g) excited state. We simultaneously record spatially resolved images of parent C 2H 4 + ions as well as photofragment C 2H 3 + and C 2H 2 + ions originating in dissociation from the vibronic excitations in two distinct bands, 7f 4 0 2 and 8f 0 0 0, at roughly the same total energy. By analyzing the images, we directly obtain the total translation energy distributions for the two dissociation channels and the branching between them. The results show that there exist differences for competitive dissociation pathways between H and H 2 elimination from C 2H 4 + depending on the vibronic preparation used, i.e., on the vibrational excitation in the ground state of the cation prior to photodissociation. Our findings are discussed in terms of the possible influence of the torsional excitation on competition between direct dissociation, isomerization, and radiationless transitions through conical intersections among the numerous electronic states that participate in the dissociation.
AB - A new imaging technique, reflection multimass velocity map ion imaging, is used to study the vibrationally mediated photodissociation dynamics in the ethylene cation. The cation ground electronic state is prepared in specific vibrational levels by two-photon resonant, three-photon ionization via vibronic bands of (π, nf) Rydberg states in the vicinity of the ionization potential of ethylene, then photodissociated through the (B̃ 2A g) excited state. We simultaneously record spatially resolved images of parent C 2H 4 + ions as well as photofragment C 2H 3 + and C 2H 2 + ions originating in dissociation from the vibronic excitations in two distinct bands, 7f 4 0 2 and 8f 0 0 0, at roughly the same total energy. By analyzing the images, we directly obtain the total translation energy distributions for the two dissociation channels and the branching between them. The results show that there exist differences for competitive dissociation pathways between H and H 2 elimination from C 2H 4 + depending on the vibronic preparation used, i.e., on the vibrational excitation in the ground state of the cation prior to photodissociation. Our findings are discussed in terms of the possible influence of the torsional excitation on competition between direct dissociation, isomerization, and radiationless transitions through conical intersections among the numerous electronic states that participate in the dissociation.
UR - http://www.scopus.com/inward/record.url?scp=25444442805&partnerID=8YFLogxK
U2 - 10.1021/jp053143m
DO - 10.1021/jp053143m
M3 - Article
C2 - 16834162
AN - SCOPUS:25444442805
SN - 1089-5639
VL - 109
SP - 7839
EP - 7842
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 35
ER -