State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, People's Republic of China.
Phys Chem Chem Phys. 2011 Nov 7;13(41):18398-408. doi: 10.1039/c1cp21345h. Epub 2011 Sep 1.
We have systematically studied Coulomb explosion of nitrogen and oxygen molecules in intense 8 and 24 fs laser pulses. In the experiment, we explicitly separated all explosion pathways through coincident measurements. The high resolution kinetic energy releases (KERs) and the exotic angular distributions of atomic ions provide direct evidence that Coulomb explosion occurs through non-Coulombic states. In the theory, we calculated dissociation potential energy curves (PECs) of nitrogen and oxygen molecules and their multicharged molecular ions using multiconfiguration second-order perturbation theory. The results indicate that Coulomb potentials are close to the accurate PECs of multicharged molecular ions only when the internuclear distance is larger than 3 Å. In comparison with the experimental observations and the theoretical calculations, we determined the internuclear distance when Coulombic explosion occurs. It is near the equilibrium distance of the neutral molecules in the case of 8 fs laser pulses and expands gradually with the increase of the charge state of the molecular ions in the case of 24 fs laser pulses.
我们系统地研究了氮和氧分子在强 8fs 和 24fs 激光脉冲中的库仑爆炸。在实验中，我们通过同时测量明确地分离了所有爆炸途径。高分辨率的动能释放（KER）和奇特的原子离子角分布为库仑爆炸通过非库仑态发生提供了直接证据。在理论方面，我们使用多组态二级微扰理论计算了氮和氧分子及其多电荷分子离子的解离势能曲线（PECs）。结果表明，只有当核间距大于 3Å 时，库仑势才接近于多电荷分子离子的精确 PEC。与实验观察和理论计算相比，我们确定了库仑爆炸发生时的核间距。在 8fs 激光脉冲的情况下，它接近中性分子的平衡距离，而在 24fs 激光脉冲的情况下，随着分子离子电荷态的增加，它逐渐扩展。
