|Budget Amount *help
¥7,200,000 (Direct Cost : ¥7,200,000)
Fiscal Year 1995 : ¥3,200,000 (Direct Cost : ¥3,200,000)
Fiscal Year 1994 : ¥4,000,000 (Direct Cost : ¥4,000,000)
The mass resolution of the reflectron time-of-flight mass spectrometer was greatly improved, and it readily allowed the assignment of the chlorine-containing compounds. Furthermore, the background signal was reduced by decreasing the temperature of the ionization chamber to a liquid nitrogen temperature. By converting second harmonic emission of the optical parametric oscillator with stimulated Raman scattering, spectrometric measurements in the vacuum ultraviolet region became possible.
First, we compared thermal decomposition and laser ablation methods in preparatioin of the sample for supersonic jet spectrometry. We found that the laser ablation technique provides a parent ion more efficiently and the thermal decomposition technique dimer and trimer ions. We also applied the present technique to the oil formed by thermal decomposition of polystirene foam used as packing materials, and found to contain various chemical species such as stirene, toluene, benzene, etc. When we applied a femtosecond excimer laser pulse (500 fs, 248 nm) to thermally decomposed products resulting from synthetic (e.g.stirene) and biological (e.g.adenine) polymers, we found that parent molecules were more efficiently formed in comparison with the case using a nanosecond pulse. Therefore, a short laser pulse was found to be useful in determination of a molecular weight.
In order to apply the present method to authentic samples, it is necessary to develop a method to assign chemical species from the signal peaks observed in the spectrum. We constructed a database using a wavemeter allowing the spectrometric measurements in an accuracy of 1/1000000. We also proposed a new method to assign the chemical species from the similarity of the spectra between the standard and the sample.