Stimulated Raman Photothermal Microscopy towards Ultrasensitive Chemical Imaging

Stimulated Raman scattering (SRS) microscopy has shown enormous potential in revealing<br> molecular structures, dynamics and couplings in complex systems. However, the sensitivity of SRS is<br> fundamentally limited to milli-molar level due to the shot noise and the small modulation depth. To<br> overcome this barrier, we revisit SRS from the perspective of energy deposition. The SRS process pumps<br> molecules to their vibrationally excited states. The thereafter relaxation heats up the surrounding and<br> induces refractive index changes. By probing the refractive index changes with a laser beam, we introduce<br> stimulated Raman photothermal (SRP) microscopy, where a &gt;500-fold boost of modulation depth is<br> achieved. Versatile applications of SRP microscopy on viral particles, cells, and tissues are demonstrated.<br> SRP microscopy opens a way to perform vibrational spectroscopic imaging with ultrahigh sensitivity. This dataset is the complete raw data used in the paper to support the findings.