Polymerization of alkyl diazoacetates [N2CHCO2R: R ) Et (1a) and Me (1b)] mediated by PdCl2 in the presence of an amine gave poly(alkoxycarbonylmethylene)s [(CHCO2R)n: R ) Et (2a,b), Me (3a,b)] bearing an ester group on every carbon atom of their main chains. MALDI-TOF-MS analyses of the polymers 2a and 3b indicated that the degree of polymerization of the polymers extended up to nearly 100. The Pd-mediated polymerization of 1a and 1b in the presence of pyridine afforded the polymers quantitatively after reprecipitation from CHCl3 into n-hexane. A mechanism of the polymerization initiated with a Pd-assisted nucleophilic attack of an amine to the monomers is proposed.

The absolute cross sections for electron-impact dissociation of octafluoro-cyclobutane (C4F8) into the neutral radicals CF, CF2, CF3 and C3F5 are measured from the threshold to 250 eV. This measurement was accomplished by appearance mass spectrometry in a dual electron beam device. The threshold energies for the neutral dissociation into CF, CF2 and CF3 are 14.5, 10.5 and 12.8 eV, respectively. The cross sections for dissociation from C4F8 into CF2 and CF are much larger than those from CF4. Besides the neutral dissociation, the cross sections for the dissociative ionization of C4F8 are extensively measured for formation of CF+, CF2 +, CF3 +, C2F3 +, C2F4 + and C3F5 +.

A full three-dimensional simulation of the ion-sensitive field-effect transistor flatband voltage shifts due to DNA immobilization and hybridization is presented. Poisson's equation is solved for a domain consisting of an electrolyte, DNA, Stern layer, linker molecular layer, and nitride layer. DNA is modeled as an insulating cylinder with discrete negative charges at the coordinates of phosphate groups. The site binding on the nitride surface significantly suppresses the flatband voltage shift due to DNA charge, while switching off the site binding gives results close to experimentally reported values. Increasing DNA density or decreasing salt concentration leads to increasing flatband voltage shifts for both immobilization and hybridization. The flatband voltage shift due to DNA hybridization is proportional to DNA density at a high salt concentration or a low DNA density. At a low salt concentration and a high DNA density, however, the flatband voltage dependence on DNA density deviates from this proportional relationship.

The energy dependence of the partial cross sections of electron-impact dissociation of SF, into the neutral radicals SF, SF, and SF, is measured from the threshold to 200eV. This measurement is accomplished by appearance mass spectrometry in a dual electron beam device. The dissociation products SF, and SF, are below the detection limit of the present system. The threshold energies for neutral dissociation into SF,, SF, and SF are measured to be 16.0, 19.5 and 22.0 eV respectively. The surface loss probability of each radical and the electron-impact nitrogen dissociation are examined to evaluate the relative dissociation cross section. However, the absolute cross section cannot be assigned for lack of the ionization cross sections for the SF, radicals. *

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