Chemiluminescence Instrument Research Articles

Imaging chemiluminescence analysis— instrumentation and applications

A chemiluminescence ( CL) instrument designed for the imaging of degradation processes is described and applications in polymer technology are given. The possibility of assessing heterogeneously distributed ageing effect is shown to be an important advantage of imaging- CL compared to ordinary non-imaging CL techniques.

Rapid chemiluminescence analysis—Instrumentation and applications

A chemiluminescence instrument is described which is designed for very rapid analyses (less than 20s) of specimens in the solid state. A number of selected experiments performed with this instrument are presented.

Systematic variations in the concentration of NOx (NO Plus NO2) at Niwot Ridge, Colorado

Measurements of the concentrations of NO and NO2 were made in the rural troposphere during a year's period in 1980–1981, during the summers of 1983, 1984, and 1987, and during the fall of 1984. The field site was located near Niwot Ridge, Colorado, at an elevation of 3 km. NO was measured with a chemiluminescence instrument, and NO2 was photolyzed to NO and measured by the same instrument. The performance of this instrument is discussed in detail. Aspects of the NOx (sum of NO and NO2) concentrations discussed include the overall distribution, the seasonal and diurnal cycles, the interannual variations, and the correlation with meteorological parameters. The meteorological dependence of [NOx] elucidates the mechanisms that transport NOx to the site. Even though the Denver urban area lies downwind from the site with respect to the prevailing winds, it is NOx from that area that predominates and is responsible for the enhanced acidic deposition and elevated ozone levels at the site. The valley‐mountain flow that is primarily responsible for this transport also may be an important mechanism for transporting anthropogenic pollution from the planetary boundary layer to the free troposphere. The major photochemical loss processes of NOx are reaction of NO2 with hydroxyl radicals to form HNO3 and the formation of PAN (peroxyacetyl nitrate) and perhaps other organic nitrates in the summer and reaction of NO2 with O3 to form NO3, N2O5, and further oxidized species in the winter.

An intercomparison of results from ferrous sulphate and photolytic converter techniques for measurements of NOx made during the NASA GTE/CITE 1 aircraft program

Two techniques designed for measurements of NOx (NO + NO2) were intercompared during aircraft flights made in the spring of 1984 in the middle free troposphere over the eastern Pacific Ocean and southwestern United States. One NO chemiluminescence instrument was equipped with a ferrous sulphate converter, another with a photolytic converter. The ferrous sulphate‐equipped instrument was apparently much less specific for NO2. It registered levels about 3 times larger than the photolytic converter and gave NO2/NO ratios that were much larger than photochemical calculations would indicate as reasonable. Additionally, the results imply that active NOx was only 10–20% of total odd nitrogen in the middle free troposphere.

Intercomparison of NO column measurements during MAP/GLOBUS 1985

Column measurements of nitric oxide were made using several techniques during the MAP/GLOBUS campaign in France in September 1985. The data sets are nearly co-located and simultaneous, therefore allowing a valid intercomparison of the various measurement methods. The range of altitudes sampled differs from instrument to instrument. This complicates the comparison because the data sets are to some extent complementary. The NO distributions apparently vary significantly from day to day, and possibly over shorter timescales. Changes in dynamics may be responsible for these variations. The results from the instruments which measure in the infrared and the ultraviolet are self-consistent, and show good agreement with photochemical predictions. On 19 September, when the intercomparison was made, the profile measured by the in-situ chemiluminescent instrument differed significantly from the predicted profile, and the measured columns were generally higher.

A comparison of the enzyme fluorometric and the peroxyoxalate chemiluminescence methods for measuring H2O2

During September 25 to October 28, 1985, the enzyme fluorometric (Lazrus et al., 1985) and the peroxyoxalate chemiluminescence (Klockow and Jacob, 1986; Jaeschke, 1986) techniques for analyzing H2O2 were compared in laboratory studies at the National Center for Atmospheric Research in Boulder, Colorado, U.S.A. and under field conditions at the Whiteface Mt. field station of the Atmospheric Sciences Research Center, Albany, New York, U.S.A. Both methods showed excellent agreement, with a maximum deviation of ±5%. Only at unusually high concentrations of some potential atmospheric species could slight interferences be observed. During the experiments the detection limits were 1.3×10-8 mol/l (0.44 ppbm) of H2O2 for the fluorometric instrument and 4×10-8 mol/l (1.36 ppbm) of H2O2 for the chemiluminescence instrument. For the chemiluminescence technique, the response to methylhydroperoxide was approximately 80-fold less than that to an equivalent concentration of H2O2.

Reactive nitrogen species in the troposphere: Measurements of NO, NO2, HNO3, particulate nitrate, peroxyacetyl nitrate (PAN), O3, and total reactive odd nitrogen (NOy) at Niwot Ridge, Colorado

Measurements of NO, NO2, HNO3, particulate nitrate, peroxyacetyl nitrate (PAN), O3, and total reactive odd nitrogen (NOy) were made in the nonurban troposphere during the summer and fall of 1984. The field site was located near Niwot Ridge, Colorado, at an elevation of 3 km. NOy was measured by catalytic reduction to NO, followed by the detection of NO with a chemiluminescence instrument. The other species were measured with conventional techniques. The data and interpretation presented focus primarily on the relationships between a measurement of NOy and concurrent measurements of the individual species, as examined through ratio and correlation plots. Through the separate display of daytime and nighttime data, the plots provide insight into the photochemical nature of the individual species. In addition, the composition of NOy is addressed through a comparison of the measured NOy level with that found for the sum of the measured component species. The NOy level systematically exceeded the sum level, with the difference being larger in the summer than in the fall. The presence of organic nitrate species other than PAN is proposed as one way to account for the observed difference.

Fast chemiluminescent method for measurement of ambient ozone

An instrument for measuring atmospheric ozone concentrations has been developed that uses chemiluminescent dyes in various solvents. Solutions of rosin Y in ethylene glycol were effective for measuring ambient ozone at a response frequency of 7 Hz and a detection limit of 0.2 ppb ozone. Other atmospheric species, including humidity, gave no interference. The response to ozone is linear over the range of 0.2-400 ppb ozone. A successful comparison of the chemiluminescent instrument to a commercial ozone analyzer was made during measurement of ambient ozone concentrations in Denver air. 11 references, 3 figures, 3 tables.

An intercomparison of nitric oxide measurement techniques

Results from an intercomparison of techniques to measure tropospheric levels of nitric oxide (NO) are discussed. The intercomparison was part of the National Aeronautics and Space Administration's Global Tropospheric Experiment and was conducted at Wallops Island, Virginia, in July 1983. Instruments intercompared included a laser‐induced fluorescence system and two chemiluminescence instruments. The intercomparisons were performed with ambient air at NO mixing ratios ranging from 10 to 60 pptv and NO‐enriched ambient air at mixing ratios from 20 to 170 pptv. All instruments sampled from a common manifold. The techniques exhibited a high degree of correlation among themselves and with changes in the NO mixing ratio. Agreement among the three techniques was placed at approximately ±30%. Within this level of agreement, no artifacts or species interferences were identified.

Nitric oxide in the upper stratosphere: Measurements and geophysical interpretation

A rocket‐borne parachute‐deployed chemiluminescence instrument has obtained seven new measurements of atmospheric nitric oxide for altitudes between 30 and 50 km at mid‐latitudes. These results, when combined with profiles measured by an earlier version of the instrument, cover all four seasons and provide a more comprehensive picture of upper stratospheric nitric oxide than has been available previously. At the highest altitudes studied, the vertical gradient in mixing ratio displays positive and negative values during different observations with the largest values tending to appear at the greatest heights in summer. Examination of the differences among the profiles, which exceed a factor of 3 near the stratopause, suggests that they arise from the action of transport processes which carry air into the mid‐latitude upper stratosphere from regions of the atmosphere that contain widely different odd‐nitrogen abundances.

Stratospheric NO measurements: A new balloon‐borne chemiluminescent instrument

A description of a new chemiluminescent balloon sonde for measuring stratospheric nitric oxide is given. First results from three flights at mid‐latitudes are presented, including measurements showing a slow reduction in NO mixing ratio beginning 2½ hours before sunset. A hysteresis in the NO mixing ratio between ascent in the morning and descent in the afternoon was observed. The afternoon values were found to be up to a factor of 2 larger than the morning values.

Device to eliminate erroneous output in cyclic chemiluminescent nitrogen dioxide monitoring

The NO 2 signal of a current cyclic chemiluminescent monitor is seriously affected by changes of the NO concentration within one cycle. A device is described to eliminate this. Instead of successive sampling for NO and NO x immediately followed by analysis, sampling is done in the NO part of the cycle for both measurements. Transportation of the NO x sample is delayed until the NO measurement has been finished. The NO 2 signal of a cyclic chemiluminescent instrument, modified in this way, showed a maximum deviation of 3% with respect to any instantaneous changes in NO concentration.

Altitude profile and sunset decay measurements of stratospheric nitric oxide

Abstract In July 1974 an NO/O3 chemiluminescent instrument was used to obtain measurements of NO in the stratosphere during two balloon flights launched from Churchill (59°N, 95°W). On the first flight, an altitude profile was obtained in which the NO volume mixing ratio was observed to increase from 0.3 to 2.7 ppbv between 19 and 29.5 km. On the second flight, the mixing ratio was observed to increase from 0.25 to 2.7 ppbv between 19 and 29 km and to remain almost constant at about 2.7 ppbv from 29 to 34.5 km. On this flight, the sunset decay of NO was also obtained while the payload was at a constant float altitude of 34.5 km. These decay measurements are compared satisfactorily with the results obtained from a time dependent stratospheric model.

An instrument for nitric oxide measurements in the stratosphere.

A completely automatic chemiluminescent instrument has been developed for in situ measurements of NO in the stratosphere. Signal intensity is linear in NO. Typical responsivity at 21.3 km is 1860 counts/sec ppbv. With a 1 sec measuring time constant, the detection limit as determined by noise is 0.03 ppbv. The instrument has been flown from balloon platforms to 30.8 km and from aircraft platforms between 12.2. and 18.3 km.

Comparison of chemiluminescent and electrochemical ozonesonde observations

The performance characteristics of the electrochemical and chemiluminescent ozonesondes were investigated through analysis of comparative ascents. A direct intercomparison of short duration was made at Boulder, Colorado, in October 1964. Further comparison was obtained by analysis of ascents made on the same day on many individual days using the electrochemical instrument at Boulder, Colorado, and the chemiluminescent instrument at Fort Collins, Colorado. Good agreement was found between the two methods of ozone measurement. Observed differences in the comparative profiles obtained in the October test series were generally within a few nanobars partial pressure. Similar results were obtained from the Boulder-Fort Collins data comparison. However, this analysis confirmed the fact that a correction is required for a systematic loss of sensitivity with time in the chemiluminescent-type sonde ascents in the winter and spring of 1963–1964.