Romanescu Constantin, Loock Hans-Peter
Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Canada ON K7L 3N6.
Phys Chem Chem Phys. 2006 Jul 7;8(25):2940-9. doi: 10.1039/b602435a. Epub 2006 Apr 21.
The photodissociation and photoionization dynamics of HBr via low-n Rydberg and ion-pair states was studied by using 2 + 1 REMPI spectroscopy and velocity map imaging of photoelectrons. Two-photon excitation at about 9.4-10 eV was used to prepare rotationally selected excited states. Following absorption of the third photon the unperturbed F (1)Delta(2) and i (3)Delta(2) states ionize directly into the ground vibrational state of the molecular ion according to the Franck-Condon principle and upon preservation of the ion core. In case of the V (1)Sigma(+)(0(+)) ion-pair state and the perturbed E (1)Sigma(+)(0(+)), g (3)Sigma(-)(0(+)), and H (1)Sigma(+)(0(+)) Rydberg states the absorption of the third photon additionally results in a long vibrational progression of HBr(+) in the X (2)Pi state as well as formation of electronically excited atomic photofragments. The vibrational excitation of the molecular ion is explained by autoionization of repulsive superexcited states into the ground state of the molecular ion. In contrast to HCl, the perturbed Rydberg states of HBr show strong participation of the direct ionization process, with ionic core preservation.
通过使用2 + 1共振增强多光子电离光谱和光电子速度成像技术，研究了HBr通过低n里德堡态和离子对态的光解离和光电离动力学。利用约9.4 - 10 eV的双光子激发来制备旋转选择的激发态。在吸收第三个光子后，未受扰动的F (1)Δ(2)和i (3)Δ(2)态根据弗兰克 - 康登原理并在保持离子核的情况下直接电离为分子离子的基振动态。对于V (1)Σ⁺(0⁺)离子对态以及受扰动的E (1)Σ⁺(0⁺)、g (3)Σ⁻(0⁺)和H (1)Σ⁺(0⁺)里德堡态，第三个光子的吸收还会导致HBr⁺在X (2)Π态中出现长振动序列以及形成电子激发的原子光碎片。分子离子的振动激发是通过排斥性超激发态自电离为分子离子的基态来解释的。与HCl不同，HBr的受扰动里德堡态在离子核保持的情况下，直接电离过程有很强的参与。
