Infrared analysis

Abstract

A new method for the infrared analysis of multicomponent gas mixtures which involves a condensed phase sampling technique employing commercially available cryogenic equipment is described. Only a few micromoles of material are required for positive qualitative identification of most chemical species; hence, the method is sensitive and suitable for impurity analysis. The technique is very general in its applicability. Structurally similar molecules are readily differentiated, and molecules differing only in isotopic content may sometimes be distinguished. Molecules are characterized by a small number of well defined frequencies. The method permits analyses to be executed rapidly and is capable of creditable quantitative results. Herein spectral analyses are demonstrated for a series of 13 Ci-C4 hydrocarbons.

Matrix isolation Fourier transform infrared spectrometry of polycyclic aromatic hydrocarbons

“…A preliminary comparison of "pulsed" deposition (16,17) with the usual continuous deposition approach has led us to conclude that the former approach offers only a small saving in time while resulting in poorer isolation of PAH molecules in the matrix. These results, coupled with the greater complexity of apparatus required to perform pulsed deposition of analytes which are not gases at room temperature, appear to indicate that pulsed deposition will not be generally useful in the IR analyses of PAH.…”

“…Since the initial description of the technique by Whittle, Dows, and Pimentel (1) in 1954, MI has been widely used, particularly for spectroscopic characterization of transient species; infrared (IR) absorption spectroscopy has often been employed in such studies (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14). However, MI-IR spectroscopy has received very little consideration as a technique for the qualitative and quantitative (15) analysis of stable species, though Rochkind (16,17) has demonstrated that a variant of the conventional MI procedure can be successfully employed for the quantitative IR analysis of specific compounds in mixtures of gases.…”

Characterization of iso-CF2I2 in frequency and ultrafast time domains

“…This mixture was deposited onto the cold window held at ϳ8 K using the pulsed deposition technique. [43][44][45][46] Typical conditions were as follows: 1 ms pulse duration, 10 Hz repetition rate, and 2 h deposition time.…”

Gas chromatography/infrared matrix isolation spectrometry

“…Application of the matrix-isolation technique as a routine analytical method for the spectroscopic identification of unknown compounds has not been widely practiced. An early application of the matrix-isolation technique to the analysis of permanent gases was demonstrated by Rochkind (4); gases were collected in inert matrices by the rapid release of small quantities of premixed sample and argon onto a cold surface. The infrared bands of the trapped species in the resulting matrices were sufficiently sharp to allow the identification of several components deposited concurrently in a matrix.…”