STM evidence of room-temperature charge instabilities inNbSe3

${\mathrm{NbSe}}_{3}$ is a quasi-low-dimensional compound with unique properties. Two incommensurate charge-density waves appear at low temperatures, which slide under the application of an electric field. The mechanism of sliding is not fully understood and it was speculated that precursor effects may be present above the onset temperatures. Scanning tunneling microscopy offers a unique tool to search for such charge instabilities and clear evidence is given for their existence at room temperature. \textcopyright{} 1996 The American Physical Society.