Development of a highly sensitive and versatile mass spectrometer system for laboratory and atmospheric measurements

More about the book

Trace gases in the upper troposphere and lower stratosphere (UTLS) significantly impact climate and tropospheric weather. Understanding the processes that govern trace gas distributions and transport is essential for improving and verifying Chemical Climate Models (CCMs), leading to more reliable climate forecasts. Two critical trace gases in the UTLS are sulphuric acid (H2SO4) and its precursor, SO2. Despite its sub-ppt mixing ratios, H2SO4 is vital for forming the stratospheric aerosol layer, which is crucial for the global radiative budget. Sensitive measurements of H2SO4 and other trace species can be achieved using mass spectrometers with chemical ionization (CI) at atmospheric pressure (AP). To enhance detection limits, improvements in the ion source and ion transfer stages are necessary, requiring optimization of ion transmission through each transfer element. Additional sensitivity can be obtained with a "brilliant" ion source, where cluster chemistry in the ion source and transfer stage is critical for measurement reliability. A specialized transfer stage was developed to provide realistic mass spectrometer measurements of ion-bound clusters and their reactions. This stage, equipped with tunable electrostatic fields, allows control over ion energy, preventing unwanted reactions. A thermally sampling atmospheric pressure ionization mass spectrometer has been constructed, enabling the sampling of cluster ions at thermal