A watch glass filled with liquid water was positioned on an EnviroESCA sample plate. A viton O-ring is used to prevent the watch glass from tumbling. The sample was analysed without any pretreatment, cleaning procedure, or electrical contacting.
The water filled watch glass underneath the analyzer nozzle at a working distance of 0.3mm. The reflection of the analyzer nozzle is clearly visible on the water surface.
The image was recorded with one of the three digital microscopes at the EnviroESCA’s analysis module. The metal pipe coming from the lower left corner allows for dosing of gases directly onto the analysed region of the sample.
The figure shows the difference in the O1s signal at different nozzle liquid surface distances. At first (green spectrum) the water surface is out of focus, meaning all analysed electrons are generated in the water vapor in front of the nozzle. With decreasing distance between nozzle and surface the intensity of the liquid part of the O1s peak increases.
When taking spectra at higher resolution two parts of the O1s peak can be clearly separated. The one at lower binding energy corresponds to electrons emitted from oxygen in the liquid water whereas the narrower part at higher binding energies correspond to oxygen in the water vapor phase.