Abstract: Apparatus and method for qualitatively and quantitatively analyzing infrared emission from excited molecules in the determination of, for example, total inorganic carbon, chloride and available chlorine in aqueous samples. Methods of exciting the gas-phase, infrared-active molecules to emit radiation include flame excitation, furnace excitation, excitation by electron impact in a gas discharge or excitation by collisions with a vibrationally excited diatomic molecule. The detector is optimized by use of dual beam system with background subtraction capabilities thereby eliminating background noise and fluctuations therein.

Abstract: Apparatus and method for qualitatively and quantitatively analyzing infrared emission from excited molecules in samples of interest is disclosed. Over the wavelength interval from 1 to 5 um, two strong emission bands are observed with a PbSe detector when organic compounds are introduced into an hydrogen/air flame. The band at 4.3 um (2326 cm.sup.-1 is due to the asymmetric stretch of carbon dioxide while the band at 2.7 um is due to both water and carbon dioxide emission. The carbon dioxide emission at 4.3 um is most intense at the tip of the flame, and increases with the amount of organic compound introduced into the flame. For chromatographic application, an optical filter can be used to isolate the 4.3 um emission band. The infrared emission detection system finds application in the determination of total inorganic carbon, chloride and available chlorine in aqueous samples.

Abstract: An improved Raman spectrometer device is provided which provides useful spectral information in situations where Raman spectroscopy has heretofore been unworkable. The spectrometer of the invention makes use of a stationary electrooptical masking device in lieu of conventional slit scanning optics, with the mask being computer controlled to provide a multiplexing function, typically employing Hadamard mathematics. The stationary encoding mask permits use of a relatively inexpensive photodiode detector, as compared with photomultiplier tubes conventionally used in Raman instrumentation. Advantageously, unwanted Rayleigh scattered radiation can be completely eliminated, either by blanking those zones of the mask receiving such radiation, or physically locating the device in such orientation that the Rayleigh scattered radiation does not pass through operative portions of the mask.