EUV ptychography combines high resolution, strong material contrast, reasonable penetration depth, and easy sample preparation. It thus has the potential to bridge the gap between visible light and electron microscopy. In this contribution, we present recent results on table-top ptychographic EUV microscopy. The experimental setup relies on a high photon flux 13.5 nm wavelength high-order harmonic source. A simple amplitude mask upstream of the sample tailors the illumination. The sample is scanned by piezo-driven stages. Finally, far-field diffraction patterns are recorded by an EUV detector and fed into a ptychographic iterative engine to retrieve both the illumination and the sample transmission in amplitude and phase. The resolution of the EUV microscope (16 nm) was characterized using a Siemens star test sample. In the next step, a thin lamella of an integrated circuit was investigated. The resulting EUV images exhibit a rich diversity in amplitude and phase. We analyzed that the relative amplitude precision is better than 4% and the absolute phase precision as good as ~ 20 mrad. In this way, the microscope provides excellent input data for further analysis of the material composition. For this purpose, the projected scattering quotient is calculated from the reconstructed phase and amplitude and compared to tabulated material parameters. Here, materials like Al, Si3N4, and SiO2 were determined with high sensitivity. Finally, biological samples, namely germlings of the filamentous fungus Aspergillus nidulans were investigated. A similar scattering quotient analysis allowed us to clearly distinguish regions with low- and high lipid and phospholipid concentrations.
Satellite observations provide unique opportunities for the identification of trace gas sources on a global scale. We present case studies for the synergistic use of satellite observations by comparing formaldehyde (HCHO) time series with fire count measurements as well as with surface temperature to identify the tropospheric sources of HCHO. The fire counts and temperature are taken as proxy for biomass burning events and vegetation activity, respectively. Both are sources of HCHO, either direct or trough photochemical oxidation of non-methane hydrocarbons (e.g. biogenic isoprene emissions). Formaldehyde time series are derived from satellite observations made by the GOME instrument. This instrument provides almost 8 years of continuous HCHO global observations, which constitute an ideal case to calculate time series over specific regions for various trace gases.
Nine regions have been selected to investigate the influence of fire counts (biomass burning proxy) and the temperature (vegetation activity proxy) on the HCHO tropospheric columns. The chosen time series has a length of 6 years (from
July 1996 to June 2002). The results show that biogenic sources of HCHO are in many cases the strongest HCHO sources. For example over south east of the USA, the correlation with temperature was very high indicating a strong biogenic source of HCHO (through isoprene emissions). The biomass burning source typically shows more pronounced
seasonal patterns or is even of sporadic nature. Over the Amazon region, the correlation with fires is high indicating that in this area most of the HCHO is caused by biomass burning. In several other regions for both sources moderate correlation coefficients were found.
SCIAMACHY (Scanning Imaging Absorption spectroMeter for Atmospheric ChartographY) is the first instrument to
allow retrieval of CO by measuring absorption in the near infrared from reflected and scattered sunlight instead of from
thermal emission. Thus, in contrast to thermal-infrared satellites (MOPITT), SCIAMACHY is highly sensitive to the
lower layers of the troposphere where the sources, such as biomass burning, are located, and where the bulk of the CO is
usually found.
In many regions of the world, the burning of vegetation has a repeating seasonal pattern, but the amount of CO emitted
from biomass burning varies considerably from place to place. Here we present a study on the relationship between fire
counts and CO vertical column densities (VCD) in different regions. These results are compared with the CO VCD from
MOPITT, aerosol index, and NO2 tropospheric VCD (TVCD) from SCIAMACHY, and the coupled chemistry climate
model (CCM) ECHAM5/MESSY.
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