PECs and photodissociation cross sections of ${\text{H}}_2^{+}$ involving $1^2{\text{Σg}}_{+}^{}$ and 1²Π_u states. Panel a: PECs of the ground state $1^2{\text{Σg}}_{+}^{}$ and excited state 1²Π_u, shown as solid gray and red lines, respectively. The corresponding rotationally excited states are indicated by dashed lines in matching colors. Panel b: photodissociation cross sections from the rotationally excited states, represented by the solid green line, which clearly exhibit three pronounced shape resonance peaks.