ION CHEMISTRY OF CLONO2 INVOLVING NO3- CORE IONS - A DETECTION SCHEMEFOR CLONO2 IN THE ATMOSPHERE

Rate constants and product branching ratios for reactions involving at mospherically interesting ions and ClONO2 have been measured. H3O+ rea cts rapidly with ClONO2, but hydrates of H3O+ do not. This implies tha t ClONO2 does not play a central role in the positive ion chemistry of the atmosphere. CO3- reacts with ClONO2 to form NO3-. Both NO3- and N O3- (H2O) react with ClONO2 to form NO3- (ClONO2). H2O does not react with NO3- (ClONO2), which is essential to the proposed in situ measure ment technique. NO3- (ClONO2) does react with HNO3 and HCI, producing NO3- (HNO3) in both cases . The reaction of NO3- (HCl) with ClONO2 als o produces NO3- (HNO3). These latter two efficient reactions, which ar e discussed in detail in a separate publication, are analogous to the efficient neutral heterogeneous reaction of HCI with ClONO2 which is i mportant in the chemistry of the Antarctic stratosphere. A detection s cheme is presented for atmospheric ClONO2 based on the reactions studi ed and utilizing mass spectrometry. A ClONO2 detection limit of 10(7) molecules cm-3 is estimated based on the operating characteristics of current ion-molecule based mass spectrometric field instruments.