Strengths and Collision Broadened Widths in the Second Overtone Band of Hydrogen Fluoride

Individual line strengths and self‐broadened half‐widths have been measured in the second overtone band of hydrogen fluoride. The electric dipole matrix element for the band has been determined from the measured strengths. Its value is:〈3∣μ(r)∣0〉exp=+1.628×10−21esu⋅cm.The m dependence of the measured half‐widths agree with the Anderson theory of collision broadening if off resonant collisions are taken into account.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70439/2/JCPSA6-57-12-5119-1.pd

LINE STRENGTHS AND COLLISION BROADENED HALF WIDTHS IN THE SECOND OVERTONE BAND OF HYDROGEN FLUORIDE

$^{1}$R. Herman and R. Wallis, J. Chem. Phys. 23, 637 (1955). $^{2}$P. W. Anderson, Phys. Rev. 76, 647 (1949).""Author Institution: The University of Michigan, Willow Run LaboratoriesAbsolute line strengths and self broadened half widths in the second overtone band of hydrogen fluoride have been measured using a high resolution 3 meter Ebert spectrometer with an average spectral resolution of $0.07 cm^{-1}$. The matrix elements of the individual lines have been determined, and their J dependence has been compared with the theory of Herman, and $Wallis^{1}$ and with numerical computations using a Morse potential and a dipole moment function emperically determined from fundamental and first and second overtone band intensity measurements. The observed half widths are in agreement with the Anderson $theory^{2}$, except that an anomalous non-linear dependence of half width on pressure has been observed for some of the lines

Comparison of open path and extractive long-path FTIR techniques in detection of air pollutants

A comprehensive comparison of long-path extractive and open-path FTIR techniques on the bases of the available literature and on our own experience at the wastewater treatment plant of a chemical factory has been made. Two equalization basins were investigated and it was supposed that all the surface of the wastewater emits polluting compounds smoothly, since the atmospheric dispersion was found to be ideal at both sites, there were no significant chemical reactions, and the basin dimensions were rather small (7 x 16m2 and 37 x 79m2, respectively). Since the possibilities were different, rather different optimal spectral parameters (resolution, scan numbers, path length) were chosen for field and laboratory measurements. The S/N ratio of laboratory spectra was about 50–100 times higher than that of field spectra, which resulted in higher precision and lower detection limits of the measurements, and comparing to field measurements an additional compound (chloroform) was detected. On the other hand, the extremely polar ammonia was not detectable by the extractive technique. With the open-path method, time-dependent concentration changes of the pollutants were monitored. The presence of the theoretically banned organic phase in wastewater was demonstrated by detection of xylenes, isopropanol, and methanol in the air above the basin. Comparing the results measured by the two different techniques the discrepancies in the concentrations were dependent on the compound under determination. In some cases, the concentrations agreed well; in other cases, not. Consequently, to application of both methods is desirable in some special cases; for example, when the extractive method is used for preliminary investigations

FTIR spectroscopy of the atmosphere Part 2. Applications

The basic principles and methods of FTIR spectroscopy of the atmosphere were summarized in our previous paper (1). Thanks to the continuous technical development of FTIR spectroscopy (increasing throughput, dynamic alignment, more sensitive detectors, brighter sources, increasing scanning speed, development of focal plane array detectors, flexible spectral manipulations and data handling, etc.) in the last decade, this method has offered a great number of unique applications. In this review article, attempt to summarize the results of the most significant and frequent applications of FTIR spectroscopy to the study of the atmosphere. The possibilities of techniques applied in this field, the extractive and open path measurement methods, and the in situ IR absorption measurements such as remote sensing using the sun, the sky, or natural hot objects as IR sources of radiation are discussed. We have made a special focus to FTIR emission spectroscopy, the so-called passive technique, since there are a number of originally hot gaseous samples such as volcanic plumes, automobile gases, stack gas plumes, or flames. Most of the subjects discussed in this article can be closely related to environmental analysis of the atmosphere. There is a wide range of atmospheric environmental applications of FTIR spectroscopy; therefore, we have focused our attention in the second part of the article on applications of FTIR spectroscopy in the atmosphere (troposphere) and stratosphere. We have summarized the basic literature in the field of special environmental applications of FTIR spectroscopy, such as power plants, petrochemical and natural gas plants, waste disposals, agricultural, and industrial sites, and the detection of gases produced in flames, in biomass burning, and in flares