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The status of the middle infrared spectroscopy of selected atmospheric trace gases, COF2, SF6, ClO, N2, and O2 is reviewed. Emphasis is placed on improved sets of spectroscopic parameters that have been included in the 1991 and 1992 versions of the HITRAN database.
Concentrations of atmospheric ozone and of ClO (the predominant form of reactive chlorine responsible for stratospheric ozone depletion) are reported for both the Arctic and Antarctic winters of the past 18 months. Chlorine in the lower stratosphere was almost completely converted to chemically reactive forms in both the northern and southern polar winter vortices. This occurred in the south long before the development of the Antarctic ozone hole, suggesting that ozone loss can be masked by influx of ozone-rich air.
Abundances of chlorine oxide (ClO) have been measured from 16 km to 30 km by a new balloon-borne in situ instrument developed from an optical design flown previously on the NASA ER-2 aircraft. This instrument, a prototype for one to be flown on the Perseus remotely piloted aircraft, was one-third the weight of that on the ER-2, yet retained the high precision and accuracy necessary for detailed photochemical studies of the lower stratosphere. In this paper we discuss the performance of the instrument during its first flight on March 31, 1991 over eastern New Mexico.
In the last years much progress has been made in the field of the detection of stratospheric trace constituents. However, only few techniques are suitable to detect ClO, one of the key constituents in ozone depletion chemistry. One of these techniques is mm-wave radiometry. This work presents the first measurements performed by a new 204 GHz radiometer at the Jungfraujoch Alpine Station.
The absorption cross sections of the ClO dimer, ClOOCl, are important to the photochemistry of ozone depletion in the Antarctic. In this work, new measurements were made of the dimer cross sections at 195 K. the results yield somewhat lower values in the long wavelength region, compared to those currently recommended in the NASA data evaluation (JPL 94-26). The corresponding solar photodissociation rates in the Antarctic are reduced by about 40%.
A Final Report of a project to measure ClO and BrO from scientific balloons launched during the Second European Stratospheric Arctic and Midlatitude Expedition (SESAME) is presented. A successful launch was initiated on February 3, 1995 in Kiruna, Sweden. A second launch on March 6, 1995 resulted in the retrieval of a partial altitude profile of these species, and a full engineering characterization of a new instrument designed for lightweight balloons.
Using observations from balloon-borne instruments and aircraft-borne instruments the investigation arrived at the following developments.: (1) Determination of the dominant catalytic cycles that destroy ozone in the lower stratosphere; (2) The partial derivatives of the rate limiting steps are observables in the lower stratosphere; (3) Recognition that the "Low NOx" condition is the regime that holds the greatest potential for misjudgement of Ozone loss rates; (4) Mapping of the Bromine radical contribution to the ozone destruction rate in the lower stratosphere; (5) Observation of OH, HO2 and ClO in the plume of the Concorde SST in the stratosphere; (6) Determination of the diurnal behavior of OH in the lower stratosphere; (7) Observed OH and H02 in the Troposphere and the interrelationship between Ozone and OH, HO2, CO and NO; (8) Analysis of the Catalytic Production of Ozone and Reactions that Couple OH and H02 in the Troposphere; (9) The continuing development of the understanding of the Tropopause temperatures, water vapor mixing ratios, and vertical advection and the mixing in of mid-latitude air; (10) Performed Multiple Tracer Analyses as a diagnostic of water vapor intrusion into the "Middle World" (i.e., the lowermost stratsophere); (11) Flight testing of a new instrument for the In Situ detection of ClON02 from the ER-2; (12) Laser induced fluorescence detection of NO2. There is included an in depth discussion of each of these developments and observations.
The objective of the research supported by this grant was the development of a new instrument to both further the technology of small, lightweight instruments for robotic aircraft and to achieve the ability to detect ClONO2, NO2, ClO and BrO from the NASA ER-2 aircraft. All of these objectives were accomplished.
The objective of the research was the development of a new small, lightweight instrument for the detection of ClONO2, NO2, ClO, and BrO, carried aboard a robotic aircraft, specifically the NASA ER-2. The schematic of the instrument is shown. Some of the observations which this instrument is designed to make are discussed. The observations of the instrument during the Photochemistry of Ozone Loss in the Arctic Region in Summer (POLARIS) mission are also reviewed.
A discharge flow apparatus with chemiluminescence detector has been used to study the reaction O + ClO --> Cl + O2, where O2 = O2(a1 delta g) or O2(b1 sigma+ g). The measured quantum yields for producing O2(a1 delta g) and O2(b1 sigma+ g) in the above reaction are less than 2.5 x 10(-2) and equal to (4.4 +/- 1.1) x 10(-4), respectively. The observed O2(a1 delta g) airglow of Venus cannot be explained in the context of standard photochemistry using our experimental results and those reported in recent literature. The possibility of an alternative source of O atoms derived from SO2 photolysis in the mesosphere of Venus is suggested.
Both the photolysis products and absorption cross sections of the ClO dimer, ClOOCl, are.
Hg3O2Cl2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Hg2+ sites. In the first Hg2+ site, Hg2+ is bonded in a 6-coordinate geometry to three equivalent O2- and three equivalent Cl1- atoms. There are a spread of Hg–O bond distances ranging from 2.25–2.42 Å. There are a spread of Hg–Cl bond distances ranging from 2.71–3.26 Å. In the second Hg2+ site, Hg2+ is bonded in a distorted linear geometry to two equivalent O2- and four equivalent Cl1- atoms. Both Hg–O bond lengths are 2.11 Å. There are two shorter (3.07 Å) and two longer (3.08 Å) Hg–Cl bond lengths. O2- is bonded to four Hg2+ atoms to form a mixture of edge and corner-sharing OHg4 tetrahedra. Cl1- is bonded in a 5-coordinate geometry to five Hg2+ atoms.
Sr2CuO2Cl2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr2+ is bonded in a 9-coordinate geometry to four equivalent O2- and five equivalent Cl1- atoms. All Sr–O bond lengths are 2.63 Å. There are four shorter (3.07 Å) and one longer (3.39 Å) Sr–Cl bond lengths. Cu2+ is bonded in a distorted square co-planar geometry to four equivalent O2- and two equivalent Cl1- atoms. All Cu–O bond lengths are 1.99 Å. Both Cu–Cl bond lengths are 2.93 Å. O2- is bonded to four equivalent Sr2+ and two equivalent Cu2+ atoms to form a mixture of corner, edge, and face-sharing OSr4Cu2 octahedra. The corner-sharing octahedral tilt angles are 0°. Cl1- is bonded in a 6-coordinate geometry to five equivalent Sr2+ and one Cu2+ atom.
Ca2CuO2Cl2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ca2+ is bonded in a 9-coordinate geometry to four equivalent O2- and five equivalent Cl1- atoms. All Ca–O bond lengths are 2.51 Å. There are four shorter (3.00 Å) and one longer (3.27 Å) Ca–Cl bond lengths. Cu2+ is bonded in a distorted square co-planar geometry to four equivalent O2- and two equivalent Cl1- atoms. All Cu–O bond lengths are 1.94 Å. Both Cu–Cl bond lengths are 2.79 Å. O2- is bonded to four equivalent Ca2+ and two equivalent Cu2+ atoms to form a mixture of corner, edge, and face-sharing OCa4Cu2 octahedra. The corner-sharing octahedral tilt angles are 0°. Cl1- is bonded in a 6-coordinate geometry to five equivalent Ca2+ and one Cu2+ atom.
PtN2H8(OCl)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of two azane;dichloroplatinum(2+);dihydrate molecules. Pt4+ is bonded in an octahedral geometry to two equivalent N3-, two equivalent O2-, and two equivalent Cl1- atoms. Both Pt–N bond lengths are 2.07 Å. Both Pt–O bond lengths are 2.05 Å. Both Pt–Cl bond lengths are 2.34 Å. N3- is bonded in a distorted trigonal non-coplanar geometry to one Pt4+ and three H1+ atoms. There are a spread of N–H bond distances ranging from 1.03–1.05 Å. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. O2- is bonded in a distorted single-bond geometry to one Pt4+ and one H1+ atom. Cl1- is bonded in a single-bond geometry to one Pt4+ atom.
CuH4(OCl)2 crystallizes in the orthorhombic Pmna space group. The structure is zero-dimensional and consists of two 10125-13-0 molecules. Cu2+ is bonded in a distorted square co-planar geometry to two equivalent O2- and two equivalent Cl1- atoms. Both Cu–O bond lengths are 1.94 Å. Both Cu–Cl bond lengths are 2.29 Å. H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. O2- is bonded in a distorted trigonal planar geometry to one Cu2+ and two equivalent H1+ atoms. Cl1- is bonded in a distorted single-bond geometry to one Cu2+ atom.
MgH4(OCl)2 crystallizes in the monoclinic C2/m space group. The structure is one-dimensional and consists of two MgH4(OCl)2 ribbons oriented in the (0, 0, 1) direction. Mg2+ is bonded to two equivalent O2- and four equivalent Cl1- atoms to form edge-sharing MgCl4O2 octahedra. Both Mg–O bond lengths are 2.04 Å. There are two shorter (2.53 Å) and two longer (2.59 Å) Mg–Cl bond lengths. H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. O2- is bonded in a distorted trigonal planar geometry to one Mg2+ and two equivalent H1+ atoms. Cl1- is bonded in an L-shaped geometry to two equivalent Mg2+ atoms.
ZnC2N4H8(OCl)2 is beta-like structured and crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of two ZnC2N4H8(OCl)2 clusters. Zn2+ is bonded in a tetrahedral geometry to two O2- and two Cl1- atoms. There are one shorter (1.98 Å) and one longer (2.03 Å) Zn–O bond lengths. There are one shorter (2.24 Å) and one longer (2.26 Å) Zn–Cl bond lengths. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal planar geometry to two N3- and one O2- atom. There is one shorter (1.34 Å) and one longer (1.35 Å) C–N bond length. The C–O bond length is 1.28 Å. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to two N3- and one O2- atom. There is one shorter (1.34 Å) and one longer (1.35 Å) C–N bond length. The C–O bond length is 1.29 Å. There are four inequivalent N3- sites. In the first N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. In the second N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. In the third N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. In the fourth N3- site, N3- is bonded in a trigonal planar geometry to one C4+ and two H1+ atoms. Both N–H bond lengths are 1.02 Å. There are eight inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one N3- atom. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Zn2+ and one C4+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Zn2+ and one C4+ atom. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Zn2+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Zn2+ atom.