A quantitative analysis of continuum absorptions in the lower stratosphere is reported based on infrared solar absorption spectra recorded in the occultation mode at 0.01 cm−1 resolution. The spectra were obtained during seven sunrises near 48°S latitude and 12 sunsets near 28°N latitude with the atmospheric trace molecule spectroscopy (ATMOS) Fourier transform spectrometer operating April 29 to May 1, 1985, on board the shuttle/Spacelab 3 platform. Continuous absorption produced primarily by the collision‐induced fundamental vibration‐rotation band of O2 and to a lesser extent by the superposition of H2O far line wings has been observed in the 1400‐ to 1800‐cm−1 interval below tangent heights of about 25 km. Continuum optical depths measured in microwindows nearly free of atmospheric line absorption are 0.78±0.06 times those calculated with the O2 absorption coefficients of Timofeyev and Tonkov (1978). This difference is consistent with previous measurements, but more than a factor of 2 improvement in accuracy has been achieved. Transmittance measurements in microwindows between 2395 and 2535 cm−1 have been used to study continuous absorption from the collision‐induced fundamental vibration‐rotation band of N2 and the far wings of strong CO2 lines (primarily those of the ν3 fundamental). Below about 2430 cm−1 there is fair agreement between the measurements and calculations based on published absorption coefficients for both N2 and CO2; at higher wave numbers, where absorption by N2 is dominant, the calculated absorption exceeds the measured absorption. The measured transmittances have been analyzed to derive best fit absorption coefficients for the N2 pressure‐induced band at lower stratospheric temperatures (∼210 K). An absorption peak has been detected near 1200 cm−1 and is believed to result from extinction by the H2SO4 stratospheric aerosol layer.

Updated volume mixing ratio profiles of C1ONO2, HC1, and HF are reported from a reanalysis and reinterpretation of solar infrared absorption spectra obtained with the Atmospheric Trace Molecule Spectroscopy instrument on board Spacelab 3 (April 29 to May 6, 1985). These analyses incorporate improved spectroscopic parameters as well as instrumental and observational corrections made to this series of infrared spectra. While the HC1 and HF results and their precisions reflect changes essentially below 30 km from the use of smaller pressure-broadened half-widths, the C1ONO 2 profiles have changed significantly as a consequence of adopting improved sets of line parameters which include a more realistic temperature dependency appropriate for stratospheric studies. The new C1ONO2 results have an overall accuracy of -+20%; when expressed in terms of vertical column abundances above their altitude span, they are in satisfactory agreement with values derived from airborne and ground based investigations.1.

Volume mixing ratio profiles of carbonyl sulfide (OCS) and hydrogen cyanide (HCN) have been deduced from the analysis of 0.01 cm-• resolution infrared solar absorption spectra obtained with the ATMOS (Atmospheric Trace Molecule Spectroscopy) Fourier transform spectrometer, operating in the occultation mode on board Spacelab 3 on April 30 to May 1, 1985. The profiles of OCS have been retrieved from spectroscopic fittings of absorption lines observed between 2038 and 2061 cm -• and identified as v 3 band transitions of OCS; they extend from 12 to 27 km altitude for sunset occultations near 28øN and from 18 to 26 km for two sunrises occurring at 46.8 ø and 49.0øS. The 28øN results agree satisfactorily with model calculations and with column density determinations by airplane above 12 km altitude. The investigation for HCN was based on the analysis of transitions belonging to both the v 3 fundamental and the 2v 2 bands of HCN, centered at 3311.48 and 1426.53 cm -x, respectively' the HCN profiles extend from 12 to 32 km for the 28øN latitude sunsets and from 13 to 30 km for sunrise events near 48øS. For both latitudes the mean results indicate a decrease of about 15 + 5% from the bottom to the top of their altitude span. The northern hemisphere retrievals reported here represent the first volume mixing ratio profiles covering the upper troposphere and the lower stratosphere simultaneously. The sunrise data provide first profiling of both species at southern mid-latitudes.

We present the initial results of our combined investigation of Raman scattering and optical absorption spectroscopy in a batch of single wall carbon nanotubes (SWNTs). The SWNT diameters are first estimated from the four radial breathing mode (RBM) peaks using a simple relation of . The calculated diameter values are related to the optical absorption peaks through the expressions of first interband transition energies, i.e., for semiconducting and for metallic SWNTs, respectively, where is the carbon-carbon bond length (0.144 nm) andγ is the energy of overlapping electrons from nearest neighbor atoms, which is 2.9 eV for a SWNT. This analysis indicates that three RBM peaks are from semiconducting tubes, and the remaining one is from metallic tubes. The detailed analysis in the present study is focused on these three peaks of the first absorption band by determining the values of the representative (n,m) pairs. The first step of analysis is to construct a list of possible (n,m) pairs from the diameters calculated from the positions of the RBM peaks. The second step is to compute the first interband transition energy, , by substituting the constructed list of (n, m) into the expression of Reich and Thomsen, and Saito et al. Finally, the pairs with the energies closest to the experimental values are selected.

Remote detection of very small amounts of aluminum hydroxide has been achieved with the use of evanescent wave absorption spectroscopy. Aluminum hydroxide is a principal corrosion product of aluminum. Five absorption bands have been recorded in the spectral range from 3350 to 3650 cm−1. The recorded positions, transition strengths, and widths of the absorption bands are in qualitative agreement with reference spectral data. A four-wavenumber-resolution Michelson interferometer and decoated 200-μm-core-diameter multimode chalcogenide optical fibers were combined to make the evanescent wave absorption measurements. One-to four-meter lengths of fiber were used with 15 to 25 cm of the fibers decoated. The technique is very sensitive and can detect a very small amount of aluminum hydroxide in contact with the decoated fiber core. This study is a valuable step in the development of a technique for monitoring industrial corrosion of aluminum alloys.