Two-photon dissociation of nitric oxide

利用脉冲激光技术研究了一氧化氮和氧化亚氮的双光子解离过程。在束流条件下，N_2O在235 ~ 240 nm范围内被双光子光解。N （^2D）、N （^2P）和NO （v=1）可以通过共振增强的多光子电离技术与飞行时间质谱技术相结合来检测。同时进行了N （^2D）和N （^2P）的多普勒剖面测量。从多普勒谱的宽度，可以确定这些物种在实验室框架中的最大速度。将这些速度与光解过程的放热特性所期望的速度进行比较，表明这些物质是在N_2O的双光子解离中形成的。三光子超激发态对这些物质的解离可以忽略。测量了N （^2D）、N （^2P）和NO （v=1）的产率以及母离子N_2O^+的产率与激发激光波数的关系。可以观察到3pssigma ^1II-X^1SIGMA^+跃迁引起的振动结构。激发到2^1_ （SIGMA^+）态比激发到其他振动能级（如1^1_和2^1_ （DELTA）态）能促进中性物质的解离。这表明预解离是通过C_S对称的解离a态进行的。最强的候选者之一是5^1A的状态。在275 nm左右的NO双光子解离过程中，可以检测到N （^2D）和O （^3P）作为产物。N （^4S）无法被检测到。比较了N （^2D）和O （^3P）的作用谱。他们都认为N （^2D）和O （^3P）的产生应该是主要的出口通道。

Two-photon dissociation processes of nitric oxide and nitrous oxide were studied by using pulsed laser techniques.N_2O was two-photon photolyzed between 235 and 240 nm under beam conditions. N (^2D), N (^2P), and NO (v=1) could be detected as products by a resonance-enhanced multiphoton ionization technique combined with a time-of-flight mass'spectrometric technique. The Doppler profile measurements of N (^2D) and N (^2P) were also carried out. From the widths of the Doppler profiles, it is possible to determined the maximum velocities of these species in the laboratory frame. Comparison of these velocities with those expected from the exothermicities of the photodissociation processes showed that these species are formed in the two-photon dissociation of N_2O.Dissociation of the three-photon super excited states to these species can be ignored. The yields of N (^2D), N (^2P), and NO (v=1) as well as that of parent N_2O^+ ions were measured as a function of the wavenumber of the excitation laser. Vibrational structures attributable to 3psigma ^1II-X^1SIGMA^+ transition could be observed. Excitation to the 2^1_ (SIGMA^+) state was found to promote the dissociation to neutral species compared to the excitation to other vibrational levels such as the 1^1_ and 2^1_ (DELTA) states. This suggests that the predissociation proceeds via a dissociative A'state in the C_S symmetry. One of the strongest candidates is the 5^1A'state.In the two-photon dissociation of NO around 275 nm, N (^2D) as well as O (^3P) could be detected as products. N (^4S) could not be detected as far as we tried. The action spectra of N (^2D) and O (^3P) were compared. They were similar suggesting that the production of N (^2D) and O (^3P) should be the main exit channe.