Transfer of a single particle for combined ESEM and TEM analyses

A new approach for transferring micrometer-sized particles between different sample holders has been developed using manipulators within an environmental scanning electron microscope (ESEM) sample chamber. Particles are transported from one sample holder to another using glass needles attached to manipulators, which allows a combination of microanalytical techniques for detailed analysis of specific particles. The technique was applied to airborne particles sampled in downtown Zurich, Switzerland. Initial, qualitative analysis of morphology and chemistry using the ESEM, led to the distinction of five particle classes. In order to investigate the structure of selected particles further, a specific particle was transferred to a transmission electron microscope (TEM) grid. The combination of analytical methods (ESEM-EDX and TEM) allowed us to characterize this particle in more detail and to identify its source. Thus, the approach presented here can be used to resolve the complex structure of single particles and to refine source apportionment based on single particle analysis.