Abstract:
In the one-color experiment at 193 nm, we studied the photodissociation of Si
2+ ions prepared by two-photon ionization using the time-sliced ion velocity map imaging method. The Si
+ imaging study shows that Si
2+ dissociation results in two distinct channels: Si(
3P
g)+Si
+(
2P
u) and Si(
1D
2)+Si
+(
2P
u). The main channel Si(
3P
g)+Si
+(
2P
u)) is produced by the dissociation of the Si
2+ ions in more than one energetically available excited electronic state, which are from the ionization of Si
2(
v=0-5). Particularly, the dissociation from the vibrationally excited Si
2(
v=1) shows the strongest signal. In contrast, the minor Si(
1D
2)+Si
+(
2P
u) channel is due to an avoided crossing between the two 2
2Π
g states in the same symmetry. It has also been observed the one-photon dissociation of Si
2+(
X4Σ
g-) into Si(1D2)+Si+(2Pu) products with a large kinetic energy release.