tailieunhanh - Analysis of the atmospheric distribution, sources, and sinks of oxygenated volatile organic chemicals based on measurements over the Pacific during TRACE-P

While it has been demonstrated that these materials have good sensitivity to polar VOCs, such as alcohols and acetone, 11,12 their rather poor response to nonpolar analytes has been viewed as a major drawback. In this report, we explored two ways to improve the sensor performance of regioregular polythiophene. The first approach is to add a second polymer at the end of the polythiophene chain to form a block copolymer. This second polymer interacts with the analytes in different ways, thus adding another dimensionality to the sensing response of the material. The second approach is to make a random copolymer of polythiophene with various side chains. Having a mixture of side chains. | JOURNAL OF GEOPHYSICAL RESEARCH VOL. 109 D15S07 doi 2003JD003883 2004 Analysis of the atmospheric distribution sources and sinks of oxygenated volatile organic chemicals based on measurements over the Pacific during TRACE-P H. B. Singh 1 L. J. Salas 1 R. B. Chatfield 1 E. Czech 1 A. Fried 2 J. Walega 2 M. J. Evans 3 B. D. Field 3 D. J. Jacob 3 D. Blake 4 B. Heikes 5 R. Talbot 6 G. Sachse 7 J. H. Crawford 7 M. A. Avery 7 S. Sandholm 8 and H. Fuelberg9 Received 18 June 2003 revised 14 October 2003 accepted 7 November 2003 published 3 June 2004. 1 Airborne measurements of a large number of oxygenated volatile organic chemicals OVOC were carried out in the Pacific troposphere km in winter spring of 2001 24 February to 10 April . Specifically these measurements included acetone CH3COCH3 methylethyl ketone CH3COC2H5 MEK methanol CH3OH ethanol C2H5OH acetaldehyde CH3CHO propionaldehyde C2H5CHO peroxyacylnitrates PANs CnH2n 1COO2NO2 and organic nitrates CnH2n 1ONO2 . Complementary measurements of formaldehyde HCHO methyl hydroperoxide CH3OOH and selected tracers were also available. OVOC were abundant in the clean troposphere and were greatly enhanced in the outflow regions from Asia. Background mixing ratios were typically highest in the lower troposphere and declined toward the upper troposphere and the lowermost stratosphere. Their total abundance SOVOC was nearly twice that of nonmethane hydrocarbons SC2-C8 NMHC . Throughout the troposphere the OH reactivity of OVOC is comparable to that of methane and far exceeds that of NMHC. A comparison of these data with western Pacific observations collected some 7 years earlier February-March 1994 did not reveal significant differences. Mixing ratios of OVOC were strongly correlated with each other as well as with tracers of fossil and biomass biofuel combustion. Analysis of the relative enhancement of selected OVOC with respect to CH3Cl and CO in 12 plumes originating from fires and sampled in the free .