Photoionization/dissociation of 1,2 propylene oxide are performed by using a time of flight mass spectrometer(TOF MS) with vacuum ultraviolet photons from Hefei synchrotron radiation source. The photoionization TOF mass spectrum and photoionization efficiency(PIE) curves of fragment ions are measured.The appearance potentials(AP) of these ions are obtained from their PIE curves. From these data, the formation enthalpies of the observed ions have been evaluated, and their possible channels have been analyzed. The mechanism of dissociative photoionization of 1,2 propylene oxide has been discussed.
In this paper,the photoionization and photodissociative ionization processes of p aminoazobenzene (pAAB,C 12 H 11 N 3) using coincidence technology with vacuum ultraviolet synchrotron radiation (SR) photoionizaton mass spectroscopy are reported.The ionization potential (IP) of this molecule and the appearance potentials (AP) of the important ionic fragments from the SR photodissociative ionization of pAAB have been measured.On the basis of the IP(C 12 H 11 N 3) and AP measured in this experiment and the IP(C 6H 5) from the literature,the dissociative energy D 0(C 6H 5-N 2C 6H 4NH 2),D 0(C 6H + 5-N 2C 6H 4NH 2),D 0(C 6H 5-N 2C 6H 4NH + 2),D 0(C 6H 5N 2-C 6H 4NH + 2) and ionization potential of free radical N 2C 6H 4NH 2 have been evaluated.Based on the results of the mass spectroscopy of pAAB obtained with SR photoionization,the possible channels of photodissociative ionization of pAAB have been analyzed.The processes(molecular ions or the fregmental ions) giving rise to the ions C 6H + 5 and C 6H 6N + need further study.
Photoionization and Photodissociation of epichlorohydrin are performed using a time-of-flight mass spectrometer（TOF-MS） with vacuum ultraviolet（VUV） photons from Hefei synchrotron radiation source. Photoionization mass spectrum and photoionization efficiency（PIE） curves of the fragment ions are measured. The appearance potentials of the fragment ions are obtained from their PIE curves. From these data, the formation enthalpies of some ions have been evaluated and their possible channels of dissociative photoionization have been discussed. The experimental results show that the mother ion of epichlorohydrin is unstable and the chlorine atom is easily lost to form ring C3H5O+ ion. Other fragment ions come from the dissociation of C3H5O+ ions.
