Raman confocal microscope Confotec NR500

SOL instruments has implemented OptiGrate’s BragGrate™ Notch Filters (BNFs) [1] in Confotec™ NR500 allowing measurements of low frequency Raman spectra (below 50 cm-1).

Low frequency Raman spectroscopy provides valuable information on a wide variety of materials, e.g. polymers (LA modes), crystals (lattice modes), carbon nanotubes (Radial breathing modes), Graphene layers (C-bands), Semiconductors (folded acoustic modes), Gases (rotation modes), pharmaceutical tablets (low frequency signatures), etc.

Fig.1 shows the low frequency Raman spectrum of Sulfur. This spectrum demonstrates the Confotec™ NR500 measurement capability (as well as the Stokes and anti-Stokes measurements).

Confotec™ NR500 system was also tested on CdI2 polytypes. The measured low frequency Raman spectra at room temperature are presented in Fig.2. Several folded modes have been observed.

A narrow peak at 15.8 cm-1 is the E2 mode of the 4H polytype (space group C64v). Two further bands correspond to Eg (45.1 cm-1) and Ag (111.3 cm-1) modes of the 2H polytype with D33d symmetry.

The interlayer shear Raman mode of few layer graphene (C-band) can be observed from 43 cm-1 (in bulk graphene) to 32 cm-1 (in bilayer graphene). In this work, we show that C-band detection is possible by utilizing Confotec™ NR500 and OptiGrate BNFs (Fig.3).

Further to previous data, various pharmaceutical tablets exhibiting low frequency Raman features were analyzed (Fig.4-6). All observed Raman peaks have frequencies very close to the excitation line.

References & Acknowledgements

  1. BragGrate™ Notch Filter: Narrow-Line Notch Filter for Ultra Low-Frequency Raman Spectroscopy.

We thank OptiGrate Corp, USA, for providing BragGrate™ Notch Filters BNF-633.

Raman spectrum of Sulfur
Fig.1. Raman spectrum of Sulfur.
Raman spectrum for Cadmium Iodide at room temperature
Fig.2. Raman spectrum for Cadmium Iodide at room temperature.
C-band of Graphene containing several layers
Рис.3. C-band of Graphene containing several layers.
Raman spectrum of Ibuprofen
Fig.4. Raman spectrum of Ibuprofen.
Raman spectrum of Aspirin (Acetylsalicylic acid)
Fig.5. Raman spectrum of Aspirin (Acetylsalicylic acid).
Raman spectrum of Acetaminophen
Fig.6. Raman spectrum of Acetaminophen.

You may also be interested in:

Help & Support

contact us