||Artist's conception of JILA's advance in atomic force microscope (AFM) design. To measure picoscale forces in liquid, a AFM probe attaches to a molecule such as DNA and pulls, and the deflection of the probe is measured. JILA researchers found that probes with the gold coating removed (purple in the illustration) make measurements that are 10 times more stable and precise than those made with conventional gold-coated probes. Gold helps reflect the laser light but it can also potentially crack, age, and creep, which degrades its mechanical properties and reduces measurement precision.
See also http://www.nist.gov/pml/div689/afm-062712.cfm.