J. Jersch et al., Direct scanning tunneling microscope detection of laser induced ultrasonicpulses with nanometer resolution, REV SCI INS, 70(12), 1999, pp. 4579-4581
We show the use of scanning tunneling microscope (STM) with a self-designed
wide-bandwidth current preamplifier (50 MHz) for direct registration of ul
trasonic pulses induced by nanosecond laser pulses in substrate. The change
s in tip-sample separation caused by ultrasonic vibrations are seen as pert
urbations in tunneling current. At moderate incident laser pulse energy of
1-2 mJ ultrasonic waves in glass rod and silica wafer were observed. This w
ide-band signal, low noise registration in addition with nanometer spatial
resolution of a STM opens new possibilities in investigations of ultrasonic
near-field distribution, elastic material properties on a nanometer scale,
and measurements of the ultrasound velocity in laser ultrasonics. (C) 1999
American Institute of Physics. [S0034-6748(99)00212-9].