丙二烯是一个具有D_(2d)对称性的典型分子。在它的基态,两个CH_2基团所在平面是互相垂直的,这与两个互相垂直的π分子轨道相对应,即两个CH_2基团的扭转角为90°。当丙二烯分子电离时,研究这个扭转角的变化是特别有趣的。众所周知,光电子谱图的各个谱带反映所研究离子的对应状态。已有几篇论文讨论基态丙二烯正离子的扭转角,但不同方法得到的 Propadiene is a typical molecule with D_ (2d) symmetry. In its ground state, the planes of two CH 2 groups are perpendicular to each other, which corresponds to two mutually perpendicular π orbitals, that is, the twist angle of two CH 2 groups is 90 °. It is particularly interesting to study this twist angle change when the allelic molecules are ionized. It is well known that the individual bands of the photoelectron spectrum reflect the corresponding states of the ions studied. Several papers have discussed the twist angle of ground-state allene positive ions, but obtained by different methods