Development of Microscopy Apparatus Switchable between Fluorescence and Ultralow-Frequency Raman Modes

Area of Science:

• Materials Science
• Spectroscopy
• Microscopy

Background:

• Characterizing nano-/micron-sized crystals requires advanced analytical techniques.
• Distinguishing between crystal polymorphs is crucial for understanding material properties.
• Existing microscopy methods may lack the versatility for comprehensive crystal analysis.

Purpose of the Study:

• To develop a novel microscopy apparatus capable of switching between fluorescence and ultralow-frequency Raman microscopy modes.
• To enable simultaneous observation of crystal morphology, fluorescence spectra, and ultralow-frequency Raman spectra.
• To demonstrate the apparatus's utility in differentiating between polymorphs of micron-sized crystals.

Main Methods:

• Development of a switchable microscopy apparatus by modifying a standard epi-illumination microscope with a removable half mirror.
• Integration of fluorescence microscopy and ultralow-frequency Raman spectroscopy (down to ~10 cm⁻¹).
• Analysis of micron-sized perylene crystals with known polymorphic forms.

Main Results:

• The developed apparatus successfully performed both fluorescence imaging/spectroscopy and ultralow-frequency Raman spectroscopy.
• Micron-sized perylene crystals exhibited distinct shapes, fluorescence spectra, and ultralow-frequency Raman spectra corresponding to their polymorphic forms.
• The apparatus clearly identified and differentiated the two perylene polymorphs using a single integrated system.

Conclusions:

• The developed switchable microscopy apparatus is a powerful and versatile tool for the analysis and characterization of nano-/micron-sized crystals.
• The ability to combine fluorescence and ultralow-frequency Raman microscopy simplifies the identification of crystal polymorphs.
• This integrated approach offers significant advantages for materials science research and crystal structure determination.