A novel ionization platform for matrix-free laser desorption/ionization-mass spectrometry (LDI-MS) was developed using self-assembled germanium nanodots (GeNDs) of uniform size (approximately 150 - 200-nm width and approximately 50-nm height) grown on a silicon wafer produced by molecular beam epitaxy. The performance of LDI-MS using GeNDs (GeND-MS) was investigated through measurements of a broad range of analytes, including peptides, proteins, synthetic oligomers, and polymer additives. Mass spectra of tryptic digests were clearly observed even for the mass range lower than m/z 800 without obstructive peaks. A detection limit of subfemtomole level was achieved for angiotensin-I. The upper limit of detectable mass range was approximately 17 kDa (myoglobin). GeND-MS also has potential for application to the characterization of industrial compounds. Almost accurate molecular weight distribution was obtained for a nonionic surfactant (Triton X-100) and for poly(ethylene glycol) oligomer. Furthermore, a brominated flame retardant, tetrabromobisphenol-A bis(2,3-dibromopropyl ether), was successfully ionized with less fragmentation, a result not obtainable by matrix-assisted laser desorption/ionization-mass spectrometry or desorption/ionization on porous silicon-mass spectrometry.

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A conjugated alternating copolymer, poly[bicarbazolylene-alt-phenylenebis(cyanovinylene)] (named PCPV), was prepared via the Knoevenagel condensation in the presence of tetrabutylammonium hydroxide. Tetrahydrofuran-soluble low molecular weight materials and insoluble polymer were obtained. The two fractions were characterized in detail by ESR and solid and solution NMR spectroscopies. Strong ESR signals were observed from the pristine PCPV polymer in both fractions. This was explained by the rotational cleavage of the cis vinylic bond to produce two π radicals, called biradicals, which diffuse along the main chains to form radical cations stabilized by conjugation in the alternating repeating moieties. In particular, the insoluble fraction shows an extremely strong and sharp line width signal with a spin concentration equal to 5.8 × 1017 spins/g. The alternating copolymer synthesized can be considered as a novel conjugated material analogous to substituted polyacetylenes with respect to the mobile unpaired electrons. The solid NMR spectrum of the insoluble fraction of the PCPV copolymer is reported for the first time. By comparison with solution NMR studies of the soluble fraction and of a model compound of the repeating unit, the structure of the copolymer was established. The 1H NMR spectrum of the soluble fraction allowed calculation of the DPn whose values roughly agree with that estimated by SEC measurements. However, the NMR signals of the soluble fraction were somewhat broadened because of the presence of unpaired electrons in the main chains.