Abstract

The availability of manned laboratory facilities in space offers wonderful opportunities and challenges in combustion science and technology. In turn, the fundamentals of combustion science can be studied purposefully through spectroscopic characterization of free radicals produced in the course of combustion. Well-studied free radicals (that are also well described theoretically and are therefore the best combustion model subjects) are hydroxyl (OH)¹ and methoxy (CH₃O),^2,3 which have analytically convenient excitation bands located in the 280–298 nm spectral region. Analytical equipment for routine laser-induced-fluorescence (LIF) experiments with these radicals usually comprises an excimer laser delivering over 0.1J of energy for photolyzing the precursor and a tunable ultraviolet laser consisting of a dye laser and a doubling stage for excitation of the fluorescence from the free radicals.⁴ It is hardly possible to use such equipment in space because it is extremely cumbersome and energy consuming. To the best of our knowledge, there have been no attempts to devise a portable unit suitable for spectroscopic measurements on free radicals in space. Such a development could significantly promote microgravity combustion science and applications. In the present paper, we substantiate our choice of the LIF excitation source, describe the experimental arrangement, and represent the results of our initial experiments aimed at demonstrating the possibility of devising a reliable portable unit for routine LIF experiments in space involving the hydroxyl and methoxy radicals.

© 1995 Optical Society of America