GC–MPI–MS of Pentachlorodibenzofurans in Flue Gas Using a UV Picosecond Laser

Pentachlorodibenzofurans (pentaCDFs) are measured by means of gas chromatography combined with multiphoton ionization–mass spectrometry (GC–MPI–MS) using a picosecond Nd:YAG laser (266 nm) as an ionization source. In this study, the pre-treated sample was collected from flue gas in an incinerator. The pentaCDF isomers in the environment were determined, for the first time, by GC–MPI–MS. In addition, the details of the fragment patterns of mono—pentaCDFs were discussed, resulting in the detection of M⁺–COCl as a major fragment ion for all of them. On the other hand, the fragment peak of M⁺–Cl was quite small, suggesting that a molecular ion (e.g., tetraCDF⁺) can easily be identified without any interference by the M⁺–Cl fragment ion (e.g., pentaCDF⁺–Cl).     

Vanishing N = 20 shell gap: study of excited states in (27,28)Ne

This Letter reports on the (1)H((28)Ne, (28)Ne) and (1)H((28)Ne, (27)Ne) reactions studied at intermediate energy using a liquid hydrogen target. From the cross section populating the first 2(+) excited state of (28)Ne, and using the previously determined BE(2) value, the neutron quadrupole transition matrix element has been calculated to be M(n)=13.8 +/- 3.7 fm(2). In the neutron knockout reaction, two low-lying excited states were populated in (27)Ne. Only one of them can be interpreted by the sd shell model while the additional state may intrude from the fp shell. These experimental observations are consistent with the presence of fp shell configurations at low excitation energy in (27,28)Ne nuclei caused by a vanishing N=20 shell gap at Z=10.