Atomic force microscopy for the analysis of environmental particles

In this study, atomic force microscopy (AFM) was evaluated as an alternativ e to electron microscopy for analysis of nano- to micron-sized environmenta l particles, such as atmospheric aerosols. The wide range of conditions und er which AFM can be conducted allows for "reactive" imaging. For example, c ollected particles can be imaged under ambient conditions and re-imaged as a function of time in order to evaluate changes. Chemical information about individual particles can be obtained in two ways: (I) by monitoring relati ve reaction rates when the sample is exposed to a reactive gas, and (2) by determination of the magnitude of interaction forces between the AFM tip an d individual particles. The combined advantages of digital, three-dimension al morphological information, no vacuum requirements, virtually no sample p reparation, and real-time imaging during reaction, make AFM an excellent te chnique for analysis of environmental particles. (C) 1999 Elsevier Science B.V. All rights reserved.