Absorption-Based Far-Field Label-Free Super-Resolution Microscopy

Abstract

Materials absorptionAbsorption, which happensLabel free in all light–matterResolutionsuper- interactions, has been studied systematically and inspires various chemical-specific measurement methods for extensive non-fluorescent species. In this chapter, we review recent achievementsMicroscopylabel free (LFM) ofLabel free far-fieldMicroscopyfar-field label-freeLabel free super-resolutionResolutionsuper- microscopySuper resolution (LFSRM)Microscopysuper-resolution that deploys materials absorption to provide the contrast. In theLinear absorption linear absorption Absorptionmodalities, samples convert photon energyEnergyto heatHeat efficiently, which turns the photothermalDetectionphotothermal detection with single-moleculeSingle molecule sensitivitySensitivity into possible. The photothermal microscope breaks the diffraction limitDiffraction limit of the excitationExcitation beam by probing the localized thermalThermal lens effect using a shorter-wavelengthWavelength beam. In the nonlinear absorptionNon-linear absorption modalities, one pumpPump beamPump beam profile could be engineered to doughnutDoughnutshape and reduce the size of the nonlinear region, which helps achieve sub-diffractionSub-diffraction resolution. Both mechanismsMechanisms use the intrinsic vibrational or electronic absorptionAbsorption of molecules, through which different species are readily discriminated. Owing to the chemical specificity and high sensitivitySensitivity, this label-freeLabel free LFSRM provides unique advantages in various materials andBiomedical in biomedicalImagingbiomedical applications, including nanomaterial inspection and in vivo imaging of living cellsCellliving and organismsOrganisms.