We present a newly constructed, two-channel thermal dissociation cavity ring-down spectrometer (TD-CRDS) for the measurement of NO_x (NO+NO₂), NO_y (${\mathrm{NO}}_x+{\mathrm{HNO}}_{\mathrm{3}}+{\mathrm{RO}}_{\mathrm{2}}{\mathrm{NO}}_{\mathrm{2}}+\mathrm{2}{\mathrm{N}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{5}}$ etc.), NO_z (NO_y−NO_x) and particulate nitrate (pNit). NO_y-containing trace gases are detected as NO₂ by the CRDS at 405 nm following sampling through inlets at ambient temperature (NO_x) or at 850 ^∘C (NO_y). In both cases, O₃ was added to the air sample directly upstream of the cavities to convert NO (either ambient or formed in the 850 ^∘C oven) to NO₂. An activated carbon denuder was used to remove gas-phase components of NO_y when sampling pNit. Detection limits, defined as the 2σ precision for 1 min averaging, are 40 pptv for both NO_x and NO_y. The total measurement uncertainties (at 50 % relative humidity, RH) in the NO_x and NO_y channels are 11 %+10 pptv and 16 %+14 pptv for NO_z respectively. Thermograms of various trace gases of the NO_z family confirm stoichiometric conversion to NO₂ (and/or NO) at the oven temperature and rule out significant interferences from NH₃ detection (<2 %) or radical recombination reactions under ambient conditions. While fulfilling the requirement of high particle transmission (>80 % between 30 and 400 nm) and essentially complete removal of reactive nitrogen under dry conditions (>99 %), the denuder suffered from NO_x breakthrough and memory effects (i.e. release of stored NO_y) under humid conditions, which may potentially bias measurements of particle nitrate. Summertime NO_x measurements obtained from a ship sailing through the Red Sea, Indian Ocean and Arabian Gulf (NO_x levels from <20 pptv to 25 ppbv) were in excellent agreement with those taken by a chemiluminescence detector of NO and NO₂. A data set obtained locally under vastly different conditions (urban location in winter) revealed large diel variations in the NO_z to NO_y ratio which could be attributed to the impact of local emissions by road traffic.

中文翻译：

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用热解离腔衰荡光谱仪（TD-CRDS）测量NO _x和NO _y：仪器表征和首次部署

我们提出了一种新型的两通道热解离腔衰荡光谱仪（TD-CRDS），用于测量 NO _x（NO + NO ₂），NO _y（${\mathrm{没有}}_X+{\mathrm{硝酸}}_{\mathrm{3}}+{\mathrm{反渗透}}_{\mathrm{2}}{\mathrm{没有}}_{\mathrm{2}}+\mathrm{2}{\mathrm{ñ}}_{\mathrm{2}}{\mathrm{Ø}}_{\mathrm{5}}$等），NO _z（NO _y -NO _x）和硝酸盐颗粒（pNit）。NO _ÿ含微量气体检测为NO ₂通过在405nm以下，在环境温度（通过入口采样的CRDS NO _X）或在850  ^∘ C（NO _Ý）。在这两种情况下， 直径：₃加入到空气样品腔的直接上游为NO（环境温度或形成在850转换 ^∘ ℃的烘箱），以 NO ₂。使用活性炭剥蚀器去除NO _y的气相成分采样pNit时。定义为平均1分钟的2σ精度的检测极限，对于NO _x 和NO _y均为40 pptv 。总的测量的不确定性（在50％相对湿度，RH）在 NO _X和NO _ÿ通道是11  ％ 10  PPTV和16  ％ 14  PPTV为NO _ž分别。NO _z族各种痕量气体的热分析图 证实了化学计量转换为NO ₂（和/或NO）在烤箱温度下，并排除了 在环境条件下NH ₃ 检测（<2％）或自由基重组反应的重大干扰。同时满足高的颗粒传输的要求（> 80  30和400nm之间％），并且基本上完全除去干条件下（反应性氮的> 99  ％），从所遭受的溶蚀NO _X突破和记忆效应（即存储的释放NO _y）在潮湿条件下，这可能会使硝酸盐颗粒的测量值产生偏差。夏季NO _x从航行通过红海，印度洋和阿拉伯湾的船上获得的测量值（NO _x水平从<20  pptv到25 ppbv）与化学发光检测NO和NO _{2的测量结果}非常吻合。在完全不同的条件下（冬季在城市中）在本地获得的数据集显示，NO _z与NO _y的比值存在较大的diel变化，这可能归因于道路交通对当地排放的影响。