Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Wearing a single DNA molecule with an AFM tip   While the fundamental limit on the resolution achieved in an atomic force
microscope (AFM) is clearly related to the tip radius, the fact that the tip
can creep and/or wear during an experiment is often ignored. This is mainly due
to the difficulty in characterizing the tip, and in particular a lack of
reliable methods that can achieve this in situ. Here, we provide an in situ
method to characterize the tip radius and monitor tip creep and/or wear and
biomolecular sample wear in ambient dynamic AFM. This is achieved by monitoring
the dynamics of the cantilever and the critical free amplitude to observe a
switch from the attractive to the repulsive regime. The method is exemplified
on the mechanically heterogeneous sample of single DNA molecules bound to mica
mineral surfaces. Simultaneous monitoring of apparent height and width of
single DNA molecules while detecting variations in the tip radius R as small as
one nanometer are demonstrated. The yield stress can be readily exceeded for
sharp tips (R<10 nm) at typical operating amplitudes (A>10nm). The ability to
know the AFM tip radius in situ and in real-time opens up the future for
quantitative nanoscale materials properties determination at the highest
possible spatial resolution.

3
The categories of this paper are: physics
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs
2
The categories of this paper are: math