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Polychlorinated biphenyls (PCBs) in transformer and food oils were measured using gas chromatography combined with multiphoton ionization mass spectroscopy. An ultrashort laser pulse emitting in the far-ultraviolet region was utilized for efficient ionization of the analytes. Numerous signal peaks were clearly observed for a standard sample mixture of PCBs when the third and fourth harmonic emissions...
In order to suppress the fragmentation and improve the sensitivity for determination of nitrated polycyclic aromatic hydrocarbons (NPAHs), the mechanism of multiphoton ionization was studied for the following representative NPAHs, 9-nitroanthracene, 3-nitrofluoranthene, and 1-nitropyrene. The analytes were extracted from the PM 2.5 on the sampling filter ultrasonically, and were measured using...
A new method for the determination of particle size was developed using optical chromatography. After separating polystyrene particles, the laser power was gradually reduced, permitting the elution of small to large particles. Particle size was calculated from the laser power when the particle was eluted with a medium flow. This approach is more accurate than the technique previously reported because...
In this review article, I report the structure and characteristics of a diode laser and the figure of merits in the application to analytical spectroscopy. This diode laser is currently used in absorption-based and fluorescence-based spectrometries. Due to their ultra-high detectability, single atoms and molecules can be detected in the extreme case. Moreover, selectivity is improved by time-resolved...
Mass spectra and ionization efficiencies of adenine were measured with nanosecond (15 ns) and femtosecond (500 fs) laser pulses at identical energy levels. A molecular ion is clearly observed in both spectra, but the efficiency is improved 10-fold when a femtosecond laser is used, indicating the distinct advantage of ultrashort laser pulses for multiphoton ionization of nucleobases in supersonic...
A technique based on pattern recognition of data obtained by supersonic jet spectrometry is employed for the prediction of chemical structure. The degree of similarity is evaluated quantitatively by calculating a cross correlation factor between sample and reference molecules. A probability density function is determined by fitting the data to a specified equation. The functional group and its position...
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