CHARACTERIZATION OF ULTRAFINE AEROSOL-PARTICLES ADSORBED ON HIGHLY ORIENTED PYROLYTIC-GRAPHITE BY SCANNING TUNNELING AND ATOMIC-FORCE MICROSCOPY

Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) are applied in studying nanometer-sized particles. Silver and carbon particles suspended in N2 are electro-statically precipitated onto a cleaved substrate (highly oriented pyrolytic graphite, HOPG). The STM and AFM investigations reveal only a very few particles being firmly attached to the substrate compared to the particle concentration in the gas. Conventional transmission electron microscopy (TEM) is used to compare the amount of precipitated particles on identical samples. According to our STM and AFM data, particles are moved by the influence of the scanning-sensor tip. Furthermore, all particles imaged with up to atomic resolution appear to be very flat. This implies a selective mechanism by which most of the particles are removed from the imaged area by the tip. These results are discussed in view of manipulating individual particles and performing local experiments with the versatile scanning probe microscopy technique. © 1993 by Academic Press, Inc.