The photoionization-dissociation patterns of neutral clusters M(NH3)(n) (M = 1,4-dioxane) were studied by synchrotron radiation and TOF mass spectrometry. The observed major product cations are protonated cluster ions M(NH3)(n)H+, and the intensities of unprotonated cluster ions M(NH3)(n)(+) are much lower. This phenomenon was also investigated with ab initio MO theory. The calculated results show that the neutral cluster M(NH3)(2) is vertically ionized into the unstable cation M-NH3-N+*H-3 and the cation easily undergoes a fast barrierless proton-transfer process to form the stable intermediate M(NH3)H+-NH2, then the intermediate dissociates into a protonated ionic cluster M(NH3)H+ and a radical NH2.

The photodissociation of CF3I at 248 nm was performed on our high-resolution photofragment translational spectrometer. For further improvement of the resolution, we have taken the following procedures: (1) Kr was used as carrier gas, (2) optimum molecular beam angle theta(opt) (when V-MB 1 V-CM) was selected, (3) the longitudinal molecular beam angle spread was reduced, and (4) the ionization region for photofragments was diminished. The photofragment translational spectra of I (P-2(1/2)) reveal eight well-resolved vibrational peaks. The highest peak was assigned to be v(2) = 5 of the v(2) vibrational mode, and then the dissociation energy would be D-0 (C-I) = 18 810 +/- 200 cm(-1) = 53.8 +/- 0.6 kcal/mol. (C) 2003 Elsevier B.V. All rights reserved.

The THF/H 2O binary clusters have been studied by the molecular beam, the VUV from synchrotron radiation and the TOF mass spectrometry technique. The (THF) n (H 2O) mH + (n = 2 ∼ 5, m = 0 ∼ n - 1) cluster ions were observed in the mass spectroscopy. It was noticed that the (THF) n (H 2O) n-2H + (n = 2 ∼ 5) cluster ions had larger intensity than the others and were regarded as "magic number" ions. By using ab initio MO method at HF/3 - 21G basis set level, the structures of (THF) n (H 2O) n-2H + (n = 2 ∼ 4) cluster ions have been optimized. The theoretical calculations help to explain the "magic number" appearance in the experiment and are in agreement with the experimental results.

The photoionization-dissociation pattern of 1,4-dioxane has been studied by molecular beam. VUV from Synchrotron Radiation and TOF mass spectrometry. The possible fragmentation channel and structures of ion fragments (m/e 41 28 20 55 57) have been discussed on the basis of PIE curves, and a rearrangement reaction mechanism for the photoionization-dissociation of 1,4-dioxane has been proposed.

The kinetic processes of the photoionization and dissociation of 4H-furan have been investigated by using synchrontron radiation. The IP of 4H-furan and APs of other ions are gotten from the spectra aka possible channels or dissociative photo ionization have been analyzed. A serices of stable clusters composed of (THF)(n)(H2O)(n-2)H+ (n=2,3,4,5) are present in the MS and the possible structures of the clusters are given.

A more complete theory of photoemission in the Millikan-Pope-Arnold (MPA) experiment is presented. The geometry of the electric field around a charged spherical particle suspended in a uniform electric field in N2 gas, as well as the energetics of the photoemitted electron, are included. No account is yet taken of electron-gas interactions or of electron diffusion in the gas. The yield of photoemission is calculated as a function of the particle charge, radius, and density, for different electron energies. The results are in good agreement with experimental data on photoemission from spherical carbon particles, but electron diffusion is seen to be important.