TY - JOUR
T1 - Adsorbate deformation as a contrast mechanism in STM images of biopolymers in an aqueous environment
T2 - images of the unstained, hydrated DNA double helix.
AU - Lindsay, S. M.
AU - Thundat, T.
AU - Nagahara, L.
PY - 1988/10
Y1 - 1988/10
N2 - A stable residual aggregate remains on a submerged gold surface after electrophoretic deposition of DNA. We present scanning tunnelling microscope (STM) images of these aggregates which show many objects with the geometry of DNA, clearly displaying the 3.4 nm helix pitch. These images are quite distinctive, and cannot be generated when the deposition technique is used without DNA in the buffer solution. A characteristic of these images is that the tip is observed to dip down over the DNA molecule at the same time as the apparent barrier height drops by a factor of about four. The tip displacement is accounted for by a model in which contrast is dominated by local fluctuations in the deformability of the adsorbate layer, a quantity deduced from measurements of the apparent barrier heights in air, water, over small molecule adsorbates, and over DNA.
AB - A stable residual aggregate remains on a submerged gold surface after electrophoretic deposition of DNA. We present scanning tunnelling microscope (STM) images of these aggregates which show many objects with the geometry of DNA, clearly displaying the 3.4 nm helix pitch. These images are quite distinctive, and cannot be generated when the deposition technique is used without DNA in the buffer solution. A characteristic of these images is that the tip is observed to dip down over the DNA molecule at the same time as the apparent barrier height drops by a factor of about four. The tip displacement is accounted for by a model in which contrast is dominated by local fluctuations in the deformability of the adsorbate layer, a quantity deduced from measurements of the apparent barrier heights in air, water, over small molecule adsorbates, and over DNA.
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M3 - Article
C2 - 3246690
SN - 0022-2720
VL - 152
JO - Journal of Microscopy
JF - Journal of Microscopy
ER -