Method development for atmospheric chemistry

The study of atmospheric processes requires sensitive and selective measurement methods to detect postulated trace substances in the atmosphere and in the laboratory. Often, known measurement methods lack the sensitivity required to quantify these substances, some of which must be detected at ultra-trace levels. As these trace substances are often of fundamental importance for understanding atmospheric processes, the development of new, sensitive methods represents a key task in atmospheric chemistry. A key example is the detection of OH radicals – the so-called ‘detergent of the atmosphere’ — which occurs in the atmosphere only at ppq concentrations (1 ppq corresponds to one particle in^10¹⁵ = 1,000,000,000,000,000 air particles). Despite these low concentrations, the OH radical is responsible for the majority of all pollutant degradation processes.

Listed below are measuring instruments that have been developed in recent years at the Department of Physical Chemistry in Wuppertal:

• LOPAP (Long Path Absorption Photometer) for the detection of nitrous acid (HONO), nitric acid (HNO_₃), nitrogen dioxide (NO_₂), nitric oxide (NO) and ozone (O_₃).
• Further development of commercial measuring instruments
• Mass spectrometric methods (MS)