Microspectroscopy

Microspectroscopy is the collective term for spectroscopic techniques used to analyze chemical composition and structure at microscopic spatial scales.

The most common modalities include Raman microspectroscopy, infrared (IR) microspectroscopy and fluorescence microspectroscopy. Raman uses inelastic scattering to probe molecular vibrations; FTIR microspectroscopy uses infrared absorption with a microscope to map chemical constituents.

Instruments combine a light microscope with a spectrograph or spectrometer and a detector such as a CCD or InGaAs array. Techniques may employ confocal optics to improve depth resolution. Hyperspectral imaging collects spectra at each pixel to produce data cubes.

Spatial resolution is limited by diffraction; typical Raman/IR microspectroscopy achieves micrometer-scale resolution, though near-field methods like tip-enhanced Raman (TERS) or near-field IR push toward nanoscale.

Applications include mapping chemical composition in biological tissues, cells and biomaterials; characterizing polymers and composites; investigating mineralogical samples; forensic analysis; quality control in semiconductors and catalysis; and studying energy storage materials.

Limitations include weak signals for some techniques, fluorescence background, sample preparation issues, and the need for spectral interpretation with reference data. Calibration, standards, and advanced data processing (multivariate analysis) are often used.

Recent advances focus on hyperspectral imaging, faster detectors, portable micro-spectroscopy, and correlative imaging combining spectroscopy with electron microscopy or scanning probe methods.