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1717937 
Journal Article 
A chemical ionization technique for measurement of pernitric acid in the upper troposphere and the polar boundary layer 
Slusher, DL; Pitteri, SJ; Haman, BJ; Tanner, DJ; Huey, LG 
2001 
Yes 
Geophysical Research Letters
ISSN: 0094-8276
EISSN: 1944-8007 
28 
20 
3875-3878 
WOS:000171588000013 
The potential of SF(6)(-) for the detection of pernitric acid in air by chemical ionization mass spectrometry was studied in the laboratory via its reactions with HO(2)NO(2), O(3), H(2)O, and NO(2). Measurements of HO(2)NO(2) using SF(6)(-) ion chemistry were then performed at the South Pole. SF(6)(-) reacts at the gas kinetic rate with HO(2)NO(2) to form SF(5)(-), NO(4)(-)(HF), NO(2)(-)(HF), and NO(3)(-), The NO(4)(-)(HF) product provides a unique signature for HO(2)NO(2). The rate coefficient for this channel is 2.9 X 10(-10) cm(3) molecule(-1) s(-1) at 16.5 torr in N(2) and decreases as the total pressure increases. NO(4)(-)(HF) undergoes ligand switching with H(2)O and HO(2)NO(2), implying the existence of a NO(4)(-) core ion in the gas phase. SF(6)(-) reacts with H(2)O to produce a large number of product ions that increase nonlinearly with [H(2)O]. This limits the use of SF(6)(-) to regions of the atmosphere with low absolute humidities. However, our lab studies indicate that HO(2)NO(2) can be selectively detected in air with an ozone mixing ratio up to 550 ppbv and a dew point of -25 degreesC or less, which corresponds to regions of the troposphere where HO(2)NO(2) is expected to be thermally stable. We present field data from the South Pole showing typical HO(2)NO(2) mixing ratios of 20 pptv.