Scanning force microscope studies of detachment of nanometer adhering particulates

We employ salt particles deposited on soda lime glass substrates as a model system for particle detachment in chemically active environments. The chemical activity is provided by water vapor, and detachment is performed with the tip of a scanning force microscope. The later force required to detach nanometer-scale salt particles is a strong function of particle size and relative humidity. The peak lateral force at detachment divided by the nominal particle area yields an effective interfacial shear strength. The variation of shear strength with particle size and humidity is described in terms of chemically assisted crack growth along the salt-glass interface.