利用离子速度影象技术研究了正-溴丁烷（n-C4H9Br）在231-267nm波段的光解，得出了如下结论：正-溴丁烷（n-C4H9Br）在231-267nm波段的吸收源于基态到三个最低激发态的跃迁，这三个激发态标识为1A″、2A′和3A′；发生在这三个排斥态的势能面（PES）上的光解最终导致C4H9＋Br（^2P3/2）或C4H9＋Br^＊（^2P1／2）的产生；2A′和3A′态之间存在避免交叉（Avoided crossing）会影响最终的光解产物；从基态1A′到激发态1A″的跃迁矩垂直于对称面，也就垂直于C-Br键；从基态1A′到激发态3A′的跃迁矩平行于对称面，同时平行于C—Br键；从基态1A′到激发态2A′的跃迁矩在对称面内，且与C—Br键成53．1^＊夹角．我们也讨论了正-溴丁烷（n—C4H9Br）在234nm和267nm附近光解时的避免交叉几率（Avoided crossing probability），以及它对单通道相对产额（Relative fraction of the individual pathways）的影响．
The photodissociation dynamics of 2-iodotoluene following excitation at 266 nm have been investigated employing femtosecond time-resolved mass spectrometry. The photofragments are detected by multiphoton ionization using an intense laser field centered at 800 nm. A dissociation time of 3804-50 fs was measured from the rising time of the co-fragments of toluene radical （C7H7） and iodine atom （I）, which is attributed to the averaged time needed for the C-I bond breaking for the simultaneously excited nσ and ππ＊ states by 266 nm pump light. In addition, a probe light centered at 298.23 nm corresponding to resonance wavelength of ground-state iodine atom is used to selectively ionize ground-state iodine atoms generated from the dissociation of initially populated hσ＊ and ππ＊ states. And a rise time of 4004-50 fs is extracted from the fitting of time-dependent I＋ transient, which is in agreement with the dissociation time obtained by multiphoton ionization with 800 nm, suggesting that the main dissociative products are ground-state iodine atoms.
