Atmospheric measurements of nitric acid are relevant both in the troposphere, where it is a precursor of inorganic free radicals as well as of nitrates and aerosols1, and in the stratosphere2, where it is a principal repository of odd nitrogen3,4. Single frequency laser detection offers the possibility of distinguishing nitric acid from other atmospheric species if the effective extinction coefficient for a given laser line is known; such information on more than one line heightens the discrimination. Recently, the constants of the Hamiltonian for this band have been published5, so that the transition frequencies and relative line strengths may be calculated. This information has been combined with transmittance data at four different CO laser frequencies which are coincident with the v2 band of nitric acid such that the extinction coefficient is determined for each laser frequency. In addition, the b-component of the transition moment for the band is found at each CO laser line used; these values are consistent among themselves and overlap the earlier determination of Goldman et al. 6 within the quoted uncertainties.
{"title":"The B-Component of the Transition Moment for the v2 Band of Nitric Acid Vapor","authors":"L. Farrow, R. Richton","doi":"10.1063/1.440952","DOIUrl":"https://doi.org/10.1063/1.440952","url":null,"abstract":"Atmospheric measurements of nitric acid are relevant both in the troposphere, where it is a precursor of inorganic free radicals as well as of nitrates and aerosols1, and in the stratosphere2, where it is a principal repository of odd nitrogen3,4. Single frequency laser detection offers the possibility of distinguishing nitric acid from other atmospheric species if the effective extinction coefficient for a given laser line is known; such information on more than one line heightens the discrimination. Recently, the constants of the Hamiltonian for this band have been published5, so that the transition frequencies and relative line strengths may be calculated. This information has been combined with transmittance data at four different CO laser frequencies which are coincident with the v2 band of nitric acid such that the extinction coefficient is determined for each laser frequency. In addition, the b-component of the transition moment for the band is found at each CO laser line used; these values are consistent among themselves and overlap the earlier determination of Goldman et al. 6 within the quoted uncertainties.","PeriodicalId":199214,"journal":{"name":"Topical Meeting on Spectroscopy in Support of Atmospheric Measurements","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1981-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129174463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To date, frequency doubled tunable dye lasers operating near 282nm have been used as the excitation source in the majority of determinations of atmospheric hydroxyl radical concentrations. However, excitation at 308nm using a tunable xenon-chloride excimer laser has significant advantages over present methods. Some of these advantages are summarized below.
{"title":"Lifetimes and Quenching Rate Constants Relevant to Remote Sensing of Hydroxyl Radicals with 308nm Excitation (XeCℓ)","authors":"I. McDermid, J. Laudenslager","doi":"10.1364/sam.1980.wp13","DOIUrl":"https://doi.org/10.1364/sam.1980.wp13","url":null,"abstract":"To date, frequency doubled tunable dye lasers operating near 282nm have been used as the excitation source in the majority of determinations of atmospheric hydroxyl radical concentrations. However, excitation at 308nm using a tunable xenon-chloride excimer laser has significant advantages over present methods. Some of these advantages are summarized below.","PeriodicalId":199214,"journal":{"name":"Topical Meeting on Spectroscopy in Support of Atmospheric Measurements","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126168287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents the first results from a newly designed system for the purpose of detecting NO2 using the method of photofragmentation - laser induced fluorescence (PF-LIF). This method was proposed by Davis, et al. (1979) and by Rodgers, et al. (1979,80) for the detection of several fluorescing and non-fluorescing compounds. In this technique, the species to be detected is made to decompose into one or more vibrationally excited fluorescent species. One of these vibrationally excited photofragments is then optically pumped into an electronically excited state. A fraction of this resulting fluorescence, occurring at shorter wavelengths than the laser pump, is then sampled using appropriate long wavelength blocking filters. This allows for major discrimination against the white fluorescence background from aerosols, gas phase impurities, and the scatter chamber walls. In conventional laser induced fluorescence, this white fluorescence background can never be entirely eliminated as some of it must always fall within the bandpass of the detection system. In the PF-LIF approach, the white fluorescence noise can be reduced, at least in principle, to the level of the PMT dark count by the extensive application of long wavelength blocking filters.
{"title":"Photofragmentation - Laser Induced Fluorescence Detection of NO2","authors":"M. Rodgers, J. Bradshaw, D. Davis","doi":"10.1364/sam.1980.tup17","DOIUrl":"https://doi.org/10.1364/sam.1980.tup17","url":null,"abstract":"This paper presents the first results from a newly designed system for the purpose of detecting NO2 using the method of photofragmentation - laser induced fluorescence (PF-LIF). This method was proposed by Davis, et al. (1979) and by Rodgers, et al. (1979,80) for the detection of several fluorescing and non-fluorescing compounds. In this technique, the species to be detected is made to decompose into one or more vibrationally excited fluorescent species. One of these vibrationally excited photofragments is then optically pumped into an electronically excited state. A fraction of this resulting fluorescence, occurring at shorter wavelengths than the laser pump, is then sampled using appropriate long wavelength blocking filters. This allows for major discrimination against the white fluorescence background from aerosols, gas phase impurities, and the scatter chamber walls. In conventional laser induced fluorescence, this white fluorescence background can never be entirely eliminated as some of it must always fall within the bandpass of the detection system. In the PF-LIF approach, the white fluorescence noise can be reduced, at least in principle, to the level of the PMT dark count by the extensive application of long wavelength blocking filters.","PeriodicalId":199214,"journal":{"name":"Topical Meeting on Spectroscopy in Support of Atmospheric Measurements","volume":"357 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122808037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Weather and climate research involve the study and prediction of meteorological atmospheric properties, with regard to either short term fluctuations, or their mean values in space and time. A detailed understanding of the absorption and emission properties of the earth's atmosphere is essential to two major areas of weather and climate research. The first utilizes atmospheric absorption and emission properties to provide global monitoring of atmospheric conditions such as temperature, humidity, ozone, surface pressure and cloud cover, and ground conditions such as temperature, ground wetness and/or snow cover, and albedo. The second computes the radiative contribution to atmospheric and surface heating or cooling as a function of the above parameters. The following sections will briefly describe some of the major considerations in these areas. It will be shown that broad banded continuum features due to absorption from wings of distant lines, pressure induced absorption, or possible other sources such as water dimer absorption, are of primary importance for meteorological applications.
{"title":"Troposphere: Weather and Climate","authors":"J. Susskind","doi":"10.1364/sam.1980.ma2","DOIUrl":"https://doi.org/10.1364/sam.1980.ma2","url":null,"abstract":"Weather and climate research involve the study and prediction of meteorological atmospheric properties, with regard to either short term fluctuations, or their mean values in space and time. A detailed understanding of the absorption and emission properties of the earth's atmosphere is essential to two major areas of weather and climate research. The first utilizes atmospheric absorption and emission properties to provide global monitoring of atmospheric conditions such as temperature, humidity, ozone, surface pressure and cloud cover, and ground conditions such as temperature, ground wetness and/or snow cover, and albedo. The second computes the radiative contribution to atmospheric and surface heating or cooling as a function of the above parameters. The following sections will briefly describe some of the major considerations in these areas. It will be shown that broad banded continuum features due to absorption from wings of distant lines, pressure induced absorption, or possible other sources such as water dimer absorption, are of primary importance for meteorological applications.","PeriodicalId":199214,"journal":{"name":"Topical Meeting on Spectroscopy in Support of Atmospheric Measurements","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128394467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The spectrum of CO2 shown in Fig.1 consists of several overlapping bands. Three of these bands have been simultaneously analyzed by the technique of whole band analysis (1) to obtain estimates of parameters which allow the calculation of individual line positions, intensities, and halfwidths as well their associated uncertainties. These parameters can be used to obtain a listing, in AFGL format, of values and uncertainties for line position, intensity, halfwidth and lower state energy. These will be presented.
{"title":"Whole Band Analysis of Absorption Bands of CO2 and N2O","authors":"M. Hoke, J. Shaw, R. L. Hawkins, R. Nordstrom","doi":"10.1364/sam.1980.wp8","DOIUrl":"https://doi.org/10.1364/sam.1980.wp8","url":null,"abstract":"The spectrum of CO2 shown in Fig.1 consists of several overlapping bands. Three of these bands have been simultaneously analyzed by the technique of whole band analysis (1) to obtain estimates of parameters which allow the calculation of individual line positions, intensities, and halfwidths as well their associated uncertainties. These parameters can be used to obtain a listing, in AFGL format, of values and uncertainties for line position, intensity, halfwidth and lower state energy. These will be presented.","PeriodicalId":199214,"journal":{"name":"Topical Meeting on Spectroscopy in Support of Atmospheric Measurements","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129122842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
W. C. Bowman, A. Charo, John Kolena, F. D. De Lucia, P. Helminger
We have recently made and currently have under way extensive millimeter and submillimeter measurements on a number of important atmospheric species. As a complement to this work, we have theoretically analyzed this data with the goal of producing "complete" spectral maps of these species in the region up to 1000 GHz. Among the species studied are hydrogen peroxide (HOOH), the hydroperoxy radical (HO2), difluoromethylene (CF2), nitric acid (HNO3), nitrous acid (both cis and trans) HNO2, nitrogen dioxide (NO2), and water (H2O). Details of the theoretical techniques and illustrations based upon earlier work of the laboratory are given in another paper at this meeting.
{"title":"Recent Millimeter and Sub millimeter Observations of Species of Atmospheric Importance.†","authors":"W. C. Bowman, A. Charo, John Kolena, F. D. De Lucia, P. Helminger","doi":"10.1364/sam.1980.tup10","DOIUrl":"https://doi.org/10.1364/sam.1980.tup10","url":null,"abstract":"We have recently made and currently have under way extensive millimeter and submillimeter measurements on a number of important atmospheric species. As a complement to this work, we have theoretically analyzed this data with the goal of producing \"complete\" spectral maps of these species in the region up to 1000 GHz. Among the species studied are hydrogen peroxide (HOOH), the hydroperoxy radical (HO2), difluoromethylene (CF2), nitric acid (HNO3), nitrous acid (both cis and trans) HNO2, nitrogen dioxide (NO2), and water (H2O). Details of the theoretical techniques and illustrations based upon earlier work of the laboratory are given in another paper at this meeting.","PeriodicalId":199214,"journal":{"name":"Topical Meeting on Spectroscopy in Support of Atmospheric Measurements","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114758130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Principles of laser heterodyne measurements will be reviewed, and spectroscopic requirements for measuring stratospheric molecules from balloon and spacecraft altitudes will be presented for the infrared, sub-mm and mm regions of the spectrum.
{"title":"Heterodyne Spectroscopy","authors":"F. Allario, R. Hudson","doi":"10.1364/sam.1980.mb4","DOIUrl":"https://doi.org/10.1364/sam.1980.mb4","url":null,"abstract":"Principles of laser heterodyne measurements will be reviewed, and spectroscopic requirements for measuring stratospheric molecules from balloon and spacecraft altitudes will be presented for the infrared, sub-mm and mm regions of the spectrum.","PeriodicalId":199214,"journal":{"name":"Topical Meeting on Spectroscopy in Support of Atmospheric Measurements","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126277585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
With the advent of semi-conductor lasers and their recent application to spectroscopy (1,2), there has been a revolution in the study of infrared spectra. Use of the tunable diode laser(TDL) has permitted high resolution (<0.0001 CM−1) studies of several molecules of high current interest (C10,HNO3,SO2,CF2C12,etc.). This study is concerned with the experimental determination of the pressure broadened characteristics of a single O3 line near 1129.4 CM−1. This line has been selected by NASA as a possible candidate for remote sensing experiments using either infrared heterodyne spectroscopy or differential lidar, since it is relatively well isolated from other atmospheric lines and has significant strength. A Beer's Law experiment is performed to determine the absorption coefficients and collisional self-broadening parameters.
{"title":"Ozone Line Widths and Strengths Near 1129.4 CM−1","authors":"L. N. Majorana, G. Copeland, C. Harward","doi":"10.1364/sam.1980.wp19","DOIUrl":"https://doi.org/10.1364/sam.1980.wp19","url":null,"abstract":"With the advent of semi-conductor lasers and their recent application to spectroscopy (1,2), there has been a revolution in the study of infrared spectra. Use of the tunable diode laser(TDL) has permitted high resolution (<0.0001 CM−1) studies of several molecules of high current interest (C10,HNO3,SO2,CF2C12,etc.). This study is concerned with the experimental determination of the pressure broadened characteristics of a single O3 line near 1129.4 CM−1. This line has been selected by NASA as a possible candidate for remote sensing experiments using either infrared heterodyne spectroscopy or differential lidar, since it is relatively well isolated from other atmospheric lines and has significant strength. A Beer's Law experiment is performed to determine the absorption coefficients and collisional self-broadening parameters.","PeriodicalId":199214,"journal":{"name":"Topical Meeting on Spectroscopy in Support of Atmospheric Measurements","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127649261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Accurate models of infrared limb emissions are required to interpret measured limb radiance profiles in terms of atmospheric temperatures, densities and composition. Measurements of infrared limb emission made by the Nimbus 7 LIMS experiment will be compared to calculated emission profiles based on nearly simultaneous measurements of temperature and composition. Uncertainties in spectroscopic data as well as in the in-situ measurements and how they affect the comparability will be discussed.
{"title":"Current Capabilities in the Modeling of Infrared Limb Emission","authors":"P. Bailey","doi":"10.1364/sam.1980.tup11","DOIUrl":"https://doi.org/10.1364/sam.1980.tup11","url":null,"abstract":"Accurate models of infrared limb emissions are required to interpret measured limb radiance profiles in terms of atmospheric temperatures, densities and composition. Measurements of infrared limb emission made by the Nimbus 7 LIMS experiment will be compared to calculated emission profiles based on nearly simultaneous measurements of temperature and composition. Uncertainties in spectroscopic data as well as in the in-situ measurements and how they affect the comparability will be discussed.","PeriodicalId":199214,"journal":{"name":"Topical Meeting on Spectroscopy in Support of Atmospheric Measurements","volume":"170 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115193504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rotational transitions in a number of important stratospheric trace molecues can potentially be accurately measured by far infrared spectroscopy. HCl, OH, H2O2, HO2 and HOCl have large rotational constants due to the reduced mass of hydrogen plus other, heavier, constituents. The polyatomics in this group are all nearly symmetric prolate tops (NSPTs) having strong Q branches (b-type selection rules, ΔJ=0, ΔK=1) that are sufficiently compact to be seen as relatively sharp features in atmospheric spectra. All the molecules are characterized by reasonably large dipole moments (μb for the NSPTs) and small partition functions, if we consider only partitioning among the Ki for the NSPTs.
{"title":"Far Infrared Measurability of HCl, OH, H2O2, HO2 and HOCl","authors":"K. Chance, W. Traub","doi":"10.1364/sam.1980.tup2","DOIUrl":"https://doi.org/10.1364/sam.1980.tup2","url":null,"abstract":"Rotational transitions in a number of important stratospheric trace molecues can potentially be accurately measured by far infrared spectroscopy. HCl, OH, H2O2, HO2 and HOCl have large rotational constants due to the reduced mass of hydrogen plus other, heavier, constituents. The polyatomics in this group are all nearly symmetric prolate tops (NSPTs) having strong Q branches (b-type selection rules, ΔJ=0, ΔK=1) that are sufficiently compact to be seen as relatively sharp features in atmospheric spectra. All the molecules are characterized by reasonably large dipole moments (μb for the NSPTs) and small partition functions, if we consider only partitioning among the Ki for the NSPTs.","PeriodicalId":199214,"journal":{"name":"Topical Meeting on Spectroscopy in Support of Atmospheric Measurements","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125826635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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