Abstract

Measurement techniques based upon absorption of mid-infrared radiation (2.5 - 25 μm) have proven to be extremely attractive in numerous research, environmental and industrial applications. Studies of atmospheric trace gases in both the laboratory and the ambient environment (1-3); as well as studies of flame (4), combustion (5), and laser diagnostics (6); studies of emissions from cigarette smoke (7), automobiles (8) and power plants (9); analysis of industrial process stream compounds (10); and moisture determinations in integrated circuit packages (11) are but a few examples of the broad range of such applications. This diversity is a direct result of the fact that many constituents exhibit moderate to strong absorption features in the mid- infrared, sometimes referred to as the "fingerprint region". Obviously, to cover all such applications is well beyond the scope of this paper, and we will therefore restrict our discussion of analytical applications of high resolution IR spectroscopy to one of the fasted growing and widespread areas: laboratory and ambient environmental studies of important atmospheric trace gases. In particular, we will focus our discussion on studies utilizing tunable diode lasers (TDLs) as the infrared radiation source, although one example of measurements utilizing another IR source will also be given. Even this specific topic is too extensive to comprehensively cover in such a short review, and we thus only attempt to give a broad overview of some of the more recent analytical applications of TDLs in studying atmospheric gases. Purely spectroscopic applications, which are equally numerous and very important, are not covered here.

© 1987 Optical Society of America