적외선양자폭포레이저와 차등흡광법을 이용한 대기 중 HONO와 H2O2의 동시 연속 측정 타당성 연구

Abstract

We tested a tunable laser differential absorption spectrometer with two mid-infrared continuous-wave mode quantum cascade lasers (cw-QCLs) for simultaneous measurements of nitrous acid (HONO) and hydrogen per-oxide (H 2 O 2 ) in the remote marine atmosphere at Baengyeong Island, Korea in October 2012. Two lasers scanned frequencies that covered approximately 0.2 cm -1near at 1277.15 cm -1and 1283.3 cm -1for HONO and H 2 O 2 , respectively with resolution of about 0.001 cm -1per channel. Ambient air sample was drawn to a 260m multi-pass astigmatic sampling path cell at reduced pressure and light transmissions along predefined fre-quency ranges were detected at two peltier cooled HgCdTe detectors. The resulting one hour detection limits based on 2 s of background signal noise are 0.17 ppbv for HONO and 0.12 ppbv for H 2 O 2 . The concentrations over the measurement periods varied from below the detection limit to 0.8 ppbv for HONO, and from 0.5 ppbv to 0.8 ppbv for H 2 O 2 , respectively. Sensitivities and detection limits for QC-TILDAS of HONO and H 2 O 2 were acceptable for their continuous monitoring in the remote background air. However, we found that further improvement could be achieved by the stabilizing intensities of transmitted laser light sources and reducing the humidity interferences.