ICE Issue 9

6 Scientific Article The Israel Chemist and Chemical Engineer Issue 9 · January 2023 · Tevet 5783 Hagit Aviv is a researcher at the Department of Chemistry, Bar-Ilan University and a co-founder of the Center for Energy and Sustainability. Until recently, as the lab manager of the Device Spectroscopy Laboratory, Hagit initiated projects and collaborations to develop spectroscopy techniques using Raman spectroscopy, specifically LFRS. Previously, her post-graduate work was centered on the field of polymers, and her doctoral research dissertation focused on synthesis and characterization of iodinated nano- and macro-particles for CT and MRI imaging. Abstract: Low-frequency Raman spectroscopy (LFRS) is a branch of vibrational spectroscopy that allows easy interpretationand highly sensitive structural identification of trace amounts of chemicals based on their unique vibrational characteristics. Due to the continuous technical improvement in Raman spectroscopy, advanced development of the device has been achieved and more applications have become possible. This article illustrates the use of LFRS for unique applications such as crystalline phase identification, enantiomeric identification, and enantiomeric separation. We present a general summary of our different research efforts in the field of polarised LFRS. The aim of this article is to highlight potential applications of different types, especially applications developed to characterize organic crystalline materials. Low-frequency Raman spectroscopy – a versatile technique for material characterization and detection Hagit Aviv,a†* Vinayaka Harshothama Damle,a,b† and Yaakov R. Tischlera aDepartment of Chemistry, Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel bFaculty of Information Technology and Electrical Engineering, University of Oulu, Finland †Authors with equal contribution *Email: Overview of Raman Spectroscopy Raman spectroscopy (RS) is an optical means of probing the vibrational modes of materials. The spontaneous Raman effect is a scattering phenomenon where photons, i.e. electromagnetic radiation of a specific wavelength, interact with the analyte i.e. the material under observation in either the ground state or one of the excited rotational-vibrational states. This interaction results in promoting the molecule into a so-called “virtual energy state” for a very short period before an inelastic photon is scattered. The resulting inelastically scattered photon which is “emitted”/“scattered” can be either of higher (anti-Stokes) or lower (Stokes) energy than the incoming photon. The probability of such inelastically scattered photons is much lower than elastically scattered photons, called Rayleigh scattered photons. Upon such interaction, the resulting rotational-vibrational state of the molecule differs from its original state, before interaction with the incoming photon. The difference in energy between the original state and the new state leads to a shift in the emitted photon’s frequency, resulting in a Raman shift [1]. RS displays several advantages over other techniques such as infrared spectroscopy. For example, the quality of the signal collected is barely affected by the presence of water, allowing for its use in many applications where infrared analysis is not reliable. A representative case study is the in-situ monitoring of a fermentative process where Raman techniques outperforms any other spectroscopic approach. Nonetheless, Raman analysis in addition to its intrinsic property of lower signal strength compared to fluorescence or absorption, suffers from some difficulties such as the