【摘要】 用一束波长为 36 0 5 5nm的激光 ,通过N2 O分子的 (3+1 )共振多光子电离 (REMPI)过程制备纯净且布居完全处于X2 Π(0 0 0 )态的母体离子N2 O+ ,然后用另一束波长在 2 75— 32 8nm范围内的可调谐激光将制备的N2 O+ 离子激发至预解离电子态A2 Σ+ .实验发现 ,由于解离碎片NO+ 所具有的一定的反冲速度 ,其TOF质谱峰明显比N2 O+ 母体宽 .通过分析NO+ 碎片TOF质谱峰形状 ,得到了解离产物的总平均平动能〈ET〉 ;通过考察〈ET〉随光解能量的变化 ,发现光解能量在 32 0 0 0cm- 1 附近约 2 5 0cm- 1 的变化范围内 ,〈ET〉值由约 80 0 0cm- 1 突然减小至约 1 6 0 0cm- 1 .通过分析 ,在光解能量小于 32 0 0 0cm- 1 的区域 ,解离通道为NO+ (X1 Σ+ ) +N(4 S) ;而在光解能量大于 32 0 0 0cm- 1 的区域 ,另一个具有较高解离限的解离通道 ,NO+ (X1 Σ+ ) +N(2 D) ,开启并完全取代N(4 S)通道成为解离的惟一通道 .根据实验结果 ,对在所研究的光解能量范围内的N2 O+ 离子A2 Σ+ 电子态预解离机理进行了探讨更多还原

【Abstract】 Pure parent ions, N 2O +, populated at X 2Π(000), were prepared by (3+1) multiphoton ionization of jet cooled N 2O molecules at 360 55nm, and then were excited to different vibrational levels of predissociative A 2Σ + state by another laser in the wavelength range of 275—328nm. The total released translational energies 〈 E T〉 at different excitation energies were measured with a time of flight (TOF) spectrometer from the TOF broadenings of the NO + fragment. The 〈 E T〉 value drops abruptly from ～8000cm -1 to ～1600cm -1 at excitation energy of ～32000cm -1 . Further analysis shows that at the excitation energies below 32000cm -1 , the dissociation channel is NO +( X 1Σ +)+N( 4S), and at the energies above 32000cm -1 a new channel, NO +( X 1Σ +)+N( 2D), is opened and replaces completely the N( 4S) channel. The predissociation mechanism of the N 2O +( A 2Σ +) ions was discussed based on the experimental results.更多还原