Brouard M, Cireasa R, Clark A P, Quadrini F, Vallance C
The Department of Chemistry, University of Oxford, The Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford, UK.
Phys Chem Chem Phys. 2006 Dec 21;8(47):5549-63. doi: 10.1039/b612460g. Epub 2006 Nov 9.
In the following paper we present translational anisotropy and angular momentum polarization data for O((3)P(1)) and O((3)P(2)) products of the photodissociation of molecular oxygen at 193 nm. The data were obtained using polarized laser photodissociation coupled with resonantly enhanced multiphoton ionization and velocity-map ion imaging. Under the jet-cooled conditions employed, absorption is believed to be dominated by excitation into the Herzberg continuum. The experimental data are compared with previous experiments and theoretical calculations at this and other wavelengths. Semi-classical calculations performed by Groenenboom and van Vroonhoven [J. Chem. Phys, 2002, 116, 1965] are used to estimate the alignment parameters arising from incoherent excitation and dissociation and these are shown to agree qualitatively well with the available experimental data. Following the work of Alexander et al. [J. Chem. Phys, 2003, 118, 10566], orientation and alignment parameters arising from coherent excitation and dissociation are modelled more approximately by estimating phase differences generated subsequent to dissociation via competing adiabatic pathways leading to the same asymptotic products. These calculations lend support to the view that large values of the coherent alignment moments, but small values of the corresponding orientation moments, could arise from coherent excitation of (and subsequent dissociation via) parallel and perpendicular components of the Herzberg I, II and III transitions.
在以下论文中，我们展示了在193nm处分子氧光解离产生的O((3)P(1))和O((3)P(2))产物的平移各向异性和角动量极化数据。这些数据是通过偏振激光光解离结合共振增强多光子电离和速度映射离子成像获得的。在所采用的喷射冷却条件下，吸收被认为主要由激发到赫兹伯格连续谱中主导。将实验数据与在此波长及其他波长下的先前实验和理论计算进行了比较。Groenenboom和van Vroonhoven [《化学物理杂志》，2002年，116，1965] 进行的半经典计算用于估计由非相干激发和解离产生的取向参数，结果表明这些参数在定性上与现有实验数据吻合良好。继Alexander等人 [《化学物理杂志》，2003年，118，10566] 的工作之后，通过估计经由导致相同渐近产物的竞争绝热途径在解离后产生的相位差，对由相干激发和解离产生的取向和排列参数进行了更近似的建模。这些计算支持了这样一种观点，即赫兹伯格I、II和III跃迁的平行和垂直分量的相干激发（以及随后的解离）可能导致相干排列矩的值较大，但相应取向矩的值较小。
