Vibrational Spectroscopy Measures Terahertz, Raman

Dual-detection impulsive vibrational spectroscopy (DIVS) is a Raman spectroscopy technique. It permits monitoring two types of vibrational signals simultaneously. It offers ultrafast, real-time spectral detection over the low-frequency, or terahertz area of the Raman spectrum and the fingerprint region at a rate of 24,000 spectra per second.

The fingerprint and terahertz spectral areas provide complementary information. Simultaneously measuring both locations, the new vibrational spectroscopy technique provides a comprehensive measure that includes information about molecular structures and interactions. There are other methods for obtaining broadband Raman spectra from both regions. However, they often have a spectral acquisition rate of fewer than ten spectra per second.

The new vibrational spectroscopy approach excites Raman vibrations with ultrashort laser pulses and gathers vibrational information with Raman probe pulses. The pump pulses generate a coherent molecular vibration. The vibration causes an oscillating electron cloud, which causes an oscillatory refractive index.

Currently, the novel vibrational spectroscopy technique can analyze pure or high-concentration samples with significant vibrational information in both the terahertz and fingerprint domains in a temporally resolved manner. In the future, it could be a beneficial tool for studying polymers.

This can be especially valuable in fields such as pharmacology or polymer research, where fingerprint spectra may assess the purity or localization of targets. In contrast, the crystalline polymorphism or the polymer stress, extent, or nature of polymerization can be probed by low-frequency spectra.

Read more