1. Fundamental aspects of adsorption on individual carbon nanotubes
David Cobden, Department of Physics, University of Washington
Interactions between gases and carbon nanotubes have many potential applications in sensing. We fabricated vibrating yoctobalances from individual single-walled nanotubes, capable of single-atom sensitivity (<10-24 kg), to investigate the adsorption of gases and its interplay with electrical properties in a direct and precise way.
At temperatures around 77 K we find that noble gases form cylindrical adsorbed monolayers which exhibit dramatic phase transitions. We also see evidence for adsorption in the 1-dimensional grooves between nanotubes, and surprising changes in the conductance on adsorption.
f0 = resonance freq
Kr on a single nanotube
Vg = 8 V
incommensurate solid
2D liquid
commensurate solid
transition
phase
2D vapor I
The nanotube yoctobalance
nanotube Pt
2 mm
trench
p, T
gate electrode - Vac d s
current
grayscale = vibration
amplitude 40
120
drive frequency (MHz)
dc gate voltage (tension)
-10
+10
resonance
Ar on a pair of
nanotubes
monolayer
forming
atoms binding in groove