Development of tunable picosecond dye laser for multiphoton ionization of dioxin precursors in supersonic jet/time-of-flight mass spectrometry.

A distributed-feedback dye laser has been developed for achieving the efficient multiphoton ionization of chlorobenzene and dichlorobenzene, that is, precursor molecules of dioxins. This tunable picosecond laser with a narrow spectral line width, that is, a nearly transform-limited pulse, provides a more efficient ionization than the nanosecond laser, which is currently in use in supersonic jet spectrometry. The advantage of picosecond over nanosecond and femtosecond lasers is also discussed on the basis of the theoretical model reported in a previous paper.