A REVIEW OF RECENT NEAR-INFRARED GRATING SPECTROSCOPY
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Date
1951
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Ohio State University
Abstract
Recent papers on infrared grating spectroscopy as well as work which has come to the author's attention privately will be reviewed. Brief summary follows: Humphreys, Plyler, and Benedict at the National Bureau of Standards are pursuing their important work on standard lines in the infrared. They have remeasured the overtone of CO to correct the earlier frequencies by Lagemann, Nielsen, and Dickey, and to compare the lines with those computed by Rao. Other accurately measured spectra from this Laboratory will be reviewed. Investigation of the earth's atmosphere and study of atomic lines in the sun are being carried on by Goldberg, Mohler, McMath, and others at Michigan, by Migeotte and colleagues at Liege, and by Shaw, Chapman, and others at the Ohio State University. Beautiful atmospheric spectra and new data concerning a number of gases $CO_{2}, N_{2} O, CH_{4}$ have been reported by these investigators. In a recent search for NO in the atmosphere (at Ohio State) no evidence of it was found. At the University of Tennessee $\nu_{2}$ and $\nu_{3}$ of $C^{14} O_{2}$ have been resolved. It is suggested that intensities of these lines, if observable in atmospheric spectra, might give information on the formation of $C^{14} O_{2}$ from cosmic ray bombardment of $N^{14}$. Evidence of CO and OH in flame spectra and a discussion of the temperature of flames were given jointly by Silverman, Benedict, Plyler, and Humphreys from the Applied Physics Laboratory and the National Bureau of Standards. A vacuum-grating spectrometer of great resolving power has recently been constructed for some of this work. Thompson and co-workers at Oxford have reported spectra and constants for a number of molecules such as $CFHCH_{2}$. Evidence of a Coriolis interaction in allene similar to that found in $CH_{2} O$ was reported. At the National Research Council of Ottawa, Herzberg and colleagues have published some beautiful measurements of combination and overtone bands observed with a 21-foot grating and a multiple reflection cell of great length. Notable among their recent papers are those on HNCO and $N_{2}O$. New values of $x_{ij}$ and $\omega_{i}$ are given from about 34 analyzed bands of $N_{2}O$. The work of the Ohio State group particularly highlights the importance of vacuum instrumentation. The most important paper is that on $C_{2}H_{2}$ by Bell and Nielsen. About thirty bands have been analyzed, and new constants are given. New measurements on the disputed $3.7\mu$ band of $H_{2}S$ verify earlier work. A beautifully resolved record of the $10_{\mu} NH_{3}$ band was published by Wood, Bell, and Nielsen showing the line splitting in great detail. The University of Tennessee, cooperating with K-25 Laboratories at Oak Ridge, has carried along a number of problems: The diatomic molecules HI, DI, and CIF have been investigated. New values of the constants have been determined. Talley has completed investigation of $C_{2} D_{2}$ from 1 to $20 \mu$. with a multiple reflection cell he examined the lead sulfide region and for $C_{2} H_{2}$ filled the gap between Herzberg's photographic and Bell's near-infrared measurements. About 55 new bands have been added to the normal and deuterated acetylene data with which a consistent vibrational analysis may be attempted. With the same cell Kaylor has resolved many new bands in $CH_{4}$ and $CD_{4}$. Resolution of several bands in $F_{2}CO$ and FNO have aided Smith and Magnuson in interpreting many of the microwave lines observed fro these molecules. $ClO_{2}$ has been reexamined and an unexplained band has been found at $290 cm^{-1}$. A comparison of the molecular shape predicted from electron diffraction and infrared data will be given. Other molecules being investigated with the grating are $CF_{4}$ and $GeF_{4}$.
Description
Author Institution: Department of Physics, The University of Tennessee