Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Single-molecule optical absorption imaging by nanomechanical
  photothermal sensing at room temperature   Absorption microscopy is a powerful technique, enabling the detection of
single non- fluorescent molecules at room temperature. So far, the molecular
absorption has been probed optically via the attenuation of a probing laser.
The sensitivity of optical probing is not only restricted by background
scattering, but it is fundamentally limited by laser shot noise. Here, we
present nanomechanical photothermal microscopy, which overcomes the scattering
and shot noise limit by detecting the sample absorption directly with a
temperature sensitive substrate. We use nanomechanical silicon nitride drums,
whose resonant frequency detunes with local heating. Individual Au
nanoparticles with diameters from 10 nm - 200 nm and single molecules (Atto
633) are scanned with a 305 {\mu}W heating laser with a peak irradiance of 330
{\mu}W/{\mu}m2. Using stress-optimized drums, we achieve a sensitivity of 45
fW/sqrt(Hz), which results in a signal-to-noise ratio of >60 for a single
molecule. Our method has important consequences for a wide range of
applications, such as imaging, absorption analysis and spectrochemical analysis
of non-fluorescent samples.

37
The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
2
The categories of this paper are: math