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The Improved Limb Atmospheric Spectrometer (ILAS) was a satellite‐based solar occultation sensor that was developed by the Environment Agency of Japan (EA) to monitor and study the stratospheric ozone layer. This paper describes the characteristics of the ILAS instrument and its performance in orbit. ILAS measured the vertical distribution of ozone, nitric acid, nitrogen dioxide, nitrous oxide, methane, water vapor, temperature, pressure, and aerosol extinction coefficients at 1.6‐km vertical resolution. ILAS was equipped with two spectrometers: an infrared (IR) spectrometer with an uncooled pyroelectric linear array detector to sense between 6.21 and 11.76 μm and a visible spectrometer to monitor 753–784 nm. In addition, a Sun‐edge sensor (SES) assigned the tangent height of the instantaneous field‐of‐view (IFOV). A two‐axis gimbals control system on ILAS used two Sun position sensors to track the center of brightness of the Sun during occultation measurements. Before launch onboard the Advanced Earth Observing Satellite (ADEOS), the performance of ILAS was checked on the ground using several methods, including gas‐cell measurements, time response measurements, Sun‐tracking tests, and hollow‐cathode lamp measurements. After the launch of ADEOS on 17 August 1996, ILAS functioned successfully for 8 months of routine operation, from 30 October 1996 to 30 June 1997, collecting more than 6700 solar occultation measurements, after which time the satellite failed due to a failure in a solar paddle. The time delay response of the IR channel was characterized using stepwise IR input. Instrument functions of the ILAS IR and visible spectrometers were determined by combining theoretical optical calculations, experimental measurements using a gas‐cell before launch, and in‐orbit data. The signal‐to‐noise ratio (SNR) of each element in the IR channel was estimated to be 400–1200. In the visible channel, it was 1600–1800 for a 100% direct Sun signal. At sunset occultation, ILAS was able to track the Sun below a tangent height of 10 km in some cases. The method of determining the solar edges from the SES data worked correctly, giving adequate tangent height information for observations. Output signal levels of the SES, visible channel, and IR channel showed slight degradation during the period that ILAS was operational, which is attributed to space‐borne contaminants. However, changes in absolute signal levels do not affect data retrieval, because the solar occultation technique was self‐calibrating. Overall, ILAS worked as designed during its operation in orbit and gathered valuable data for ozone layer studies.

SummaryThe pressure dependence of fluorescence quenching of gaseous glyoxal has been measured in the presence of a magnetic field of 1-8 kG. Below 5 kG both the collision free lifetime and the collisional quenching constant were found to be dependent upon magnetic field strength. Above 5 kG the collisional quenching constant turned out to be nearly equal to the value without magnetic field and the collision free lifetime took a constant value larger than that without magnetic field.The magnetic enhancement of the intramolecular radiationless transition of gaseous molecules has been studied theoretically. The phenomenon is shown to be explained by considering two mechanisms, mechanisms I and 11. Mechanism I is due to the interaction of a primary state with secondary states through the Zeeman hamiltonian. Mechanism I1 is due to the shift and broadening of appropriate rovibronic levels by the Zeeman effect.

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Articles you may be interested inEffect of SiO2 buffer layers on the structure of SrTiO3 films grown on silicon by pulsed laser deposition Molecular beam deposited thin films of pentacene for organic field effect transistor applications Extensive control of structures of deposited polymer films has been realized when the films have been prepared on a quartz or KBr substrate by laser ablation of polyacrylonitrile ͑PAN͒ with 308 ͑XeCl͒, 248 ͑KrF͒, and 193 nm ͑ArF͒ excimer laser beams, as revealed by scanning electron microscopy, infrared spectroscopy, x-ray photoelectron spectroscopy, electron spin resonance, and x-ray diffraction measurements. The original structure of PAN is essentially retained for the films deposited by ablation at 308 nm. Deformation and elimination of nitrile groups occur for the films prepared by ablation at 248 and 193 nm, respectively. Furthermore, a remarkable power-dependent structural change has been observed at 248 nm; an increase in the laser power has led to ring closure of nitrile groups, resulting in the development of -conjugated systems. In addition, a rather high electric conductivity on the order of 10 Ϫ2 S cm Ϫ1 has been given to the films deposited by ablation at 248 and 193 nm on reirradiation with lower-power excimer laser beams of 308 nm.

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