5 research outputs found
Nanomechanical Photothermal Near Infrared Spectromicroscopy of Individual Nanorods
Understanding light-matter interaction at the nanoscale requires probing the
optical properties of matter at the individual nano-absorber level. To this
end, we have developed a nanomechanical photothermal sensing platform that can
be used as a full spectromicroscopy tool for single molecule and single
particle analysis. As a demonstration, the absorption cross-section of
individual gold nanorods is resolved from the spectroscopic and polarization
standpoint. By exploiting the capabilities of nanomechanical photothermal
spectromicroscopy, the longitudinal localized surface plasmon resonance (LSPR)
in the NIR range is unravelled and quantitatively characterized. The
polarization features of the transversal surface plasmon resonance (TSPR) in
the VIS range are also analyzed. The measurements are compared with the finite
element method (FEM), elucidating the role played by electron-surface and bulk
scattering in these plasmonic nanostructures, as well as the interaction
between the nano-absorber and the nanoresonator, ultimately resulting in
absorption strength modulation. Finally, a comprehensive comparison is
conducted, evaluating the signal-to-noise ratio of nanomechanical photothermal
spectromicroscopy against other cutting-edge single molecule and particle
spectroscopy techniques. This analysis highlights the remarkable potential of
nanomechanical photothermal spectromicroscopy due to its exceptional
sensitivity
Nanomechanical absorption spectroscopy of 2D materials with femtowatt sensitivity
Nanomechanical spectroscopy (NMS) is a recently developed approach to determine optical absorption spectra of nanoscale materials via mechanical measurements. It is based on measuring changes in the resonance frequency of a membrane resonator vs. the photon energy of incoming light. This method is a direct measurement of absorption, which has practical advantages compared to common optical spectroscopy approaches. In the case of two-dimensional (2D) materials, NMS overcomes limitations inherent to conventional optical methods, such as the complications associated with measurements at high magnetic fields and low temperatures. In this work, we develop a protocol for NMS of 2D materials that yields two orders of magnitude improved sensitivity compared to previous approaches, while being simpler to use. To this end, we use mechanical sample actuation, which simplifies the experiment and provides a reliable calibration for greater accuracy. Additionally, the use of low-stress silicon nitride membranes as our substrate reduces the noise-equivalent power to fW , comparable to commercial semiconductor photodetectors. We use our approach to spectroscopically characterize a 2D transition metal dichalcogenide (WS2), a layered magnetic semiconductor (CrPS4), and a plasmonic super-crystal consisting of gold nanoparticles
Photothermal Microscopy & Spectroscopy with Nanomechanical Resonators
In nanomechanical photothermal absorption spectroscopy and microscopy, the
measured substance becomes a part of the detection system itself, inducing a
nanomechanical resonance frequency shift upon thermal relaxation. Suspended,
nanometer-thin ceramic or 2D material resonators are innately highly-sensitive
thermal detectors of localized heat exchanges from substances on their surface
or integrated into the resonator itself. Consequently, the combined
nanoresonator-analyte system is a self-measuring spectrometer and microscope:
responding to a substances transfer of heat over the entire spectrum for which
it absorbs, according to the intensity it experiences. Limited by their own
thermostatistical fluctuation phenomena, nanoresonators have demonstrated
sufficient sensitivity for measuring trace analyte as well as single particles
and molecules with incoherent light or focused and unfocused coherent light.
They are versatile in their design, support various sampling methods and
hyphenation with other spectroscopic methods, and are capable in a wide range
of applications including fingerprinting, separation science, and surface
sciences.Comment: perspective article, 23 pages with references, 7 figure
Nanomechanical Photothermal Near Infrared Spectromicroscopy of Individual Nanorods
Understanding light-matter
interaction at the nanoscale
requires
probing the optical properties of matter at the individual nanoabsorber
level. To this end, we developed a nanomechanical photothermal sensing
platform that can be used as a full spectromicroscopy tool for single
molecule and single particle analysis. As a demonstration, the absorption
cross-section of individual gold nanorods is resolved from a spectroscopic
and polarization standpoint. By exploiting the capabilities of nanomechanical
photothermal spectromicroscopy, the longitudinal localized surface
plasmon resonance in the NIR range is unraveled and quantitatively
characterized. The polarization features of the transversal surface
plasmon resonance in the VIS range are also analyzed. The measurements
are compared with the finite element method, elucidating the role
played by electron surface and bulk scattering in these plasmonic
nanostructures, as well as the interaction between the nanoabsorber
and the nanoresonator, ultimately resulting in absorption strength
modulation. Finally, a comprehensive comparison is conducted, evaluating
the signal-to-noise ratio of nanomechanical photothermal spectroscopy
against other cutting-edge single molecule and particle spectroscopy
techniques. This analysis highlights the remarkable potential of nanomechanical
photothermal spectroscopy due to its exceptional sensitivity
Nanomechanical absorption spectroscopy of 2D materials with femtowatt sensitivity
Nanomechanical spectroscopy (NMS) is a recently developed approach to determine optical absorption spectra of nanoscale materials via mechanical measurements. It is based on measuring changes in the resonance frequency of a membrane resonator vs. the photon energy of incoming light. This method is a direct measurement of absorption, which has practical advantages compared to common optical spectroscopy approaches. In the case of two-dimensional (2D) materials, NMS overcomes limitations inherent to conventional optical methods, such as the complications associated with measurements at high magnetic fields and low temperatures. In this work, we develop a protocol for NMS of 2D materials that yields two orders of magnitude improved sensitivity compared to previous approaches, while being simpler to use. To this end, we use mechanical sample actuation, which simplifies the experiment and provides a reliable calibration for greater accuracy. Additionally, the use of low-stress silicon nitride membranes as our substrate reduces the noise-equivalent power to NEP = 890 fW H z − 1 , comparable to commercial semiconductor photodetectors. We use our approach to spectroscopically characterize a 2D transition metal dichalcogenide (WS2), a layered magnetic semiconductor (CrPS4), and a plasmonic super-crystal consisting of gold nanoparticles.</p