Hundreds-fold Sensitivity Enhancement of Photothermal Microscopy in Near-Critical Xenon.
Photothermal absorption microscopy of single Au nanoparticles was conducted at temperatures and pressures near the critical point of Xenon (Tc = 16.583 °C, Pc = 5.842 MPa). The divergence of the thermal expansion coefficient at the critical point makes the refractive index highly sensitive to changes in temperature, which directly translates to a large enhancement of the photothermal signal. We find that measurements taken near the critical point of Xe give a signal enhancement factor of up to 440 ± 130 over those taken in glycerol. The highest sensitivity recorded here corresponds to power dissipation of 64 pW, achieving a signal-to-noise ratio of 9.4 for 5 nm Au nanoparticles with an integration time of 50 ms, making this the most sensitive of any absorption microscopy technique reported to date. Enhancing the sensitivity of absorption microscopy lowers the operating heating power, allowing the technique to be more compatible with absorbers with absorption coefficient and photochemical stability lower than that of Au.
Material Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
Tina X
TX
Ding
Leiden Institute of Physics, Huygens-Kamerlingh Onnes Laboratory, Postbus 9504, 2300 RA Leiden, The Netherlands.
Lei
L
Hou
Leiden Institute of Physics, Huygens-Kamerlingh Onnes Laboratory, Postbus 9504, 2300 RA Leiden, The Netherlands.
Harmen van der
Hv
Meer
Material Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.|Kavli Energy NanoScience Institute, Berkeley, California 94720, United States.
A Paul
AP
Alivisatos
Leiden Institute of Physics, Huygens-Kamerlingh Onnes Laboratory, Postbus 9504, 2300 RA Leiden, The Netherlands.
Michel
M
Orrit