Scanning Electron Microscopy: Sample preparation secrets: How hydrocarbons background overlap is prevented during secondary ion mass spectrometry on rocks?
Sample preparation secrets
A refurbished geophysical science laboratory in a wide Midwestern Research University is now equipped with a new Focus Ion Beam Fiels Emission Scanning Electron Microscope (FIB-FESEM) and searches to maximize the use and results from their new machine. As most of their applications are related to earth science study, they regularly coat and polished sections of rocks and meteorites who generally have tiny, sometimes submicron grains. Geologists generally prepare samples for microanalysis, by coating them with gold or carbon (Gold, for secondary ion mass spectrometry as it is mono-isotopic with a low ionization yield; carbon minimizes overlap in x-ray microanalysis), also other sample metals are prepared. Nevertheless, it remains of critical and particular importance for the geologist’s laboratory to reduce hydrocarbon background during coating, as hydrocarbon background can cause overlaps when coated specimens are analyzed with secondary ion mass spectrometry.
The geology Laboratory had made a long-standing use of a 30-year-old diffusion-pump bell-jar type carbon coater and regularly numerous instances of hydrocarbon background-induced overlaps are encountered. To reduce this hydrocarbon background in spectroscopy, sample preparation with Denton Vacuum Desk V TSC, recommended by, with its turbo molecular pumping package will have a crucial role. Due to hydrocarbons backstreaming from the oil present both in any diffusion pump and also in rock samples, significant hydrocarbon background peaks are often observed in spectroscopy.
A large variety of high vacuum applications uses turbomolecular pumps especially the ones demanding clean and truly oil-free vacuum.The single-ended, turbomolecular pump is often used to replace a same size diffusion pump in existing systems. Besides the absence of oil on the backing-vacuum side, which will contribute to significant hydrocarbon background reduction when performing the Scanning Electron Microscopy (SEM) sample preparation, a turbomolecular pump provides more facility for maintenance and wear.
The following points are Desk V TSC characteristics:
- Hydrocarbon-free sample preparation
- 70 l/s turbo molecular pump
- Full range high vacuum gauge
- Capable of sputtering all metals
- Provides finer grained films
- Enhanced touchpad with graphics capability
- Manual or automatic timed sputtering or etching
- Choice of adjustable current control to permit either high or low rate sputtering to achieve finer grain structure
- Sample specimen protection from damage via Denton’s patented anode grid which, in conjunction with the magnetron sputter head to collect stray electrons, prevents them from bombarding/heating the simple.