Abstract: A method is provided for precisely and concurrently measuring dynamic engine oil consumption and fuel consumption within an internal combustion engine on a real-time basis. Nonradioactive organo- bromine or chlorine compounds are added to the oil in small amounts in their natural isotopic abundance or enriched. Upon complete combustion, the bromine or chlorine is converted into hydrogen bromide (HBr) or hydrogen chloride (HCl), respectively. A tunable diode laser spectrometer is used to determine the trace amounts of the resultant HBr or HCl in the exhaust gases, which continuously flows through a sample cell by the use of a sample line that allows the unimpeded transport of samples, reduces the pressure of the exhaust gas and maintains it at a suitable level for analysis, and prevents the condensation of water vapor in the exhaust gas so as to prevent the dissolution of the tracer compounds in the water condensate.

Abstract: A method is provided for precisely and concurrently measuring dynamic engine oil consumption and fuel consumption within an internal combustion engine in an automotive environment on a real time basis. Nonradioactive tracer compounds, such as bromine or chlorine in the form of organic bromo- or chloro-compounds are added to the engine oil in small amounts. Upon complete combustion, the bromine or chlorine is converted into either hydrogen bromide or hydrogen chloride. A sample of the exhaust gases generated by the internal combustion engine and comprising the hydrogen bromide or hydrogen chloride is collected and maintained at a pressure where distinction between an absorption line of the tracer specie and the absorption lines of a related isotopic species is discernible. Monochromatic radiation is then transmitted through the gaseous sample at the frequency of an absorption line particular to the tracer specie.

Abstract: Spectroscopic measurements of stable isotopes are performed using a tunable lead salt diode laser. The design of the system is based upon the optimization of isotopic spectral lines from two different path lengths in an absorption cell using a single gaseous sample. A short path cell to measure the more abundant species and a long path cell to measure the less abundant species are used. A micrometer adjustment of a path length is used for equalizing spectral line intensities to obtain a measure of isotope enrichment or of absolute isotopic concentration.

Abstract: Spectroscopic measurements of stable isotopes are performed using a tunable lead salt diode laser. The design of the system is based upon the optimization of isotopic spectral lines from two different path lengths in an absorption cell using a single gaseous sample. A short path cell to measure the more abundant species and a long path cell to measure the less abundant species are used. A micrometer adjustment of a path length is used for equalizing spectral line intensities to obtain a measure of isotope enrichment or of absolute isotopic concentration.