Laboratory measurement of H2O2 pressure broadening parameter for JEM/SMILES Observation from International Space Station

A new generation of sub-millimeter-wave receivers employing sensitive SIS (Superconductor Insulator Superconductor) detector technology will provide new opportunities for precise remote sensing measurements of minor constituents in the earth and planetary atmosphere.Superconducting Sub-Millimeter-Wave Limb-Emission Sounder (SMILES) was designed to be onboard the Japanese Experiment Module (JEM) on the International Space Station (ISS) as a collaboration project of National Institute of Information and Communications Technology (NICT) and Japan Aerospace Exploration Agency (JAXA).SMILES in Transfer Vehicle (HTV) plan to launch in September 11 2009 by Japanese H-IIB rocket. JEM/SMILES will allow to observe the atmospheric species such as O3, H35Cl, H37Cl, ClO, BrO, HOCl, HO2, H2O2, HNO3 and CH3CN, Ozone isotope species, and water vapor with the precisions in a few to several tens percents [1] in the altitude region upper troposphere (about 8km in mid-latitude) and the mesosphere (about 90km in mid-latitude). In this paper, laboratory measurement of the pressure broadening parameter (γ) of Hydrogen peroxide (H2O2) at JKa,Kc = 201,19 - 192,17 rotational transition (625.044 GHz) will be presented. This is one of the target transitions of JEM/SMILES observation. γ of H2O2 in sub-millimeter-wave region was measured for the first time. The measurement was carried out using a sub-millimeter-wave absorption spectrometric system in Tokyo Institute of Technology.The radiation source from a backward wave oscillator (BWO) was phase-locked to the harmonics of a synthesized sweeper with two-step phase lock loop. The BWO source frequency was modulated with the modulation frequency of 51 kHz. H2O2 sample was prerpared by distillation of commercial available 30% solution. The pressures of sample and buffer gas (N2 and O2) were controlled by a mass flow meter and monitored by two Baratron monitors in the cell. From the observed profiles of the spectrum, the pressure broadening line widths were determined using a convolution method proposed by Pickett [2], [3]. γ was determined by fitting the measured line widths to a linear function with a least-square method. γ (N2) = 4.03 ± 0.06 [MHz/Torr] (1.4%), γ (O2) = 2.49 ± 0.04 [MHz/Torr] (1.7%). The errors are presumably caused by representational accuracy fluctuation of Baratron pressure monitor. Precision of JEM/SMILES sensitive observation requires the precise value of γ of H2O2 within the error of 3%. We confirmed that the precision of the measurement fulfills the SMILES observation requirement. Refferences [1] JEM/SMILES mission plan. Version 2.1, November 15, 2002. [2] M. M. Yamada, M. Kobayashi, M. Habara, T. Amano, and B. J. Drouin, J. Quant. Spectrosc. Radiat. Transfer 82, 391-399 (2003). [3] H. M. Pickett, Appl. Opt. 19, 2745 (1980).