Shi Mian-Gong

An Experimental Observation of Axial Variation of Average Size of Methane Clusters in a Gas Jet

Axial variation of average size of methane clusters in a gas jet produced by supersonic expansion of methane through a cylindrical nozzle of 0.8 mm in diameter is observed using a Rayleigh scattering method. The scattered light intensity exhibits a power scaling on the backing pressure ranging from 16 to 50 bar, and the power is strongly Z dependent varying from 8.4 (Z = 3 mm) to 5.4 (Z = 11 mm), which is much larger than that of the argon cluster. The scattered light intensity versus axial position shows that the position of 5 mm has the maximum signal intensity. The estimation of the average cluster size on axial position Z indicates that the cluster growth process goes forward until the maximum average cluster size is reached at Z = 9 mm, and the average cluster size will decrease gradually for Z > 9 mm.

Internuclear separations from foil breakup of fast H+2, H+3, D+2 and D+3 molecules☆

Abstract Breakup fragment energy distributions from the Coulomb explosions in thin carbon foils of ~2 MeV H+2, H+3, D+2 and D+3 molecular ion beams have been measured for the incident beam direction. The energy distributions show H+3 and D+3 both to be triangular in shape. Mean values of intenuclear separations were extracted as (1.19 ± 0.03) A , (1.32 ± 0.03) A , (0.98 ± 0.02) A , and (0.93 ± 0.02) A respectively for H+2 D+2, H+3 and D+3. The H+2, and H+3 results are consistent with the previous values obtained at Argonne, Lyon and Rehovot.

Ion source effect on the bond length of 4HeH

The bond length of 4HeH+ resulting from collision-induced destruction is measured at 1.4420 MeV using the Coulomb Explosion Technique. The measured bond length of 4HeH+ is 0.094±0.003nm. The bond length of 4HeH+ obtained with our radio frequency (RF) ion source is larger than that obtained with a duoplasmatron ion source at Argonne National Laboratory (ANL), but the bond lengths of H2+ and H3+obtained separately by ANL and by us with the two different ion sources are consistent with each other, which implies that there exists an ion source effect on the bond length of 4HeH+. The main reason why the 4HeH+ bond lengths obtained by the two different ion sources are different is also discussed.