Raman Universe - a Perfect Guide to Stellar Research

In 2021, we planned to invite Horiba Scientific for a traditional, in-person workshop focused on advanced applications of Raman spectroscopy. But due to the pandemic, we had to pivot to an online event, the first virtual nano @ stanford Raman Workshop, co-hosted with our friends from Horiba Scientific, entitled Raman Universe - a Perfect Guide to Stellar Research.

This short course took place with 5, 2 hour sessions broadcast live each Tuesday. Each session consisted of a 90 minute lecture with 30 minutes of open Q&A. The agenda and titles for the first 4 sessions are posted below; the topic of the last session was selected by popular voting among registrants.

Agenda
March 16^th	Raman Spectroscopy: Fundamentals, Applications and Instrumentation Watch the recording.
March 23^rd	Raman Imaging: Visualizing the Spatial Variation of Chemical Bonding and Solid State Structure Watch the recording.
March 30^th	Raman Crystallography: Applying Raman Polarization Selection Rules in Theory and Practice Watch the recording.
April 6^th	Raman and PL at the nanoscale- why it really matters for the 2D materials Watch the recording.
April 20^th	Raman Topics chosen by Attendees: Solid state structure: Crystalline, amorphous, microcrystalline and nanocrystalline Polarized Raman Photoluminescence spectroscopy using a Raman spectrometer Stress and strain Watch the recording.

Abstracts

David Tuschel, Raman Applications Scientist, HORIBA Scientific

Raman Spectroscopy session and Raman Imaging session (March 16th and 23rd)

The first two presentations in the Stanford Raman Workshop will teach introductory Raman spectroscopy and imaging. The chemical bond origins of Raman scattering along with the instrumentation used to acquire Raman spectra and images will be explained. Resonance Raman effects and their dependence on laser excitation wavelength will be taught. Regarding instrumentation and spectral acquisition, participants will learn about lateral and axial spatial resolution, detection limits, and laser polarization in micro-Raman sampling. We will also discuss the importance of spectral resolution and how to apply it when rendering a Raman image. Regarding applications, we will show examples of how Raman spectroscopy provides insight into the energetics of molecular interactions in the liquid and vapor phases, and that it can be used to distinguish crystalline polymorphs and differentiate single crystal, polycrystalline and amorphous materials in the solid state. The effects of chemical bonding, strain and crystallite size on Raman spectra will be addressed and we will show you how to image these characteristics. In addition, we will discuss how combined spectral imaging by laser excited photoluminescence and Raman scattering can be used to reveal the spatially varying solid-state structure of materials.

David Tuschel, Raman Applications Scientist, HORIBA Scientific

Raman Crystallography session (March 30th)

This presentation will cover some basic theory and practical implications regarding the application of polarization selection rules for Raman spectroscopy of solids. In addition, we will present some clear and practical methods for the application of these rules to obtain more information about solid state structure using Raman spectroscopy. Polarization - Orientation (P-O) Raman spectroscopy can be used to identify vibrational modes, determine crystal structure, distinguish allotropes and polymorphs, differentiate single from polycrystalline materials, and determine orientation of the crystal and degree of disorder, all on a micrometer scale. P-O Raman spectroscopy can be an important analytical tool because of its complementarity to X-ray diffraction. Here, we explain the theoretical basis for P-O micro-Raman spectroscopy and provide several examples to demonstrate its feasibility and beneficial application.

Andrey Krayev, AFM-Raman Product Manager, HORIBA Scientific

Raman and PL at the Nanoscale: Why it Really Matters for the 2D Materials (April 6th)

In prior lecture we already discussed how Raman imaging can help identifying heterogeneities in 2D materials. Quite often the scale of structural or electronic or morphological heterogeneity in these materials is on the order of few tens of nanometers or less, which is beyond the spatial resolution of conventional Raman microscopy. Tip enhanced Raman scattering (TERS) and tip enhanced photoluminescence (TEPL) can address the problem of spatial resolution. In this lecture we’ll demonstrate how TERS and TEPL imaging can probe number of nanoscale heterogeneities in 2D crystals: growth related, including lateral and vertical heterostructures, substrate induced, and the morphological heterogeneities that appear (intentionally or not) in the process of exfoliation/ 2D crystal transfer. Finally, we’ll discuss a hot-fresh results on TERS imaging of reconstructed Moire patterns in twisted bilayers of graphene.

Speaker Bios

Short Biography

David Tuschel

David Tuschel is currently a Raman Applications Scientist at HORIBA Scientific. In this capacity he supports customers in applied Raman spectroscopy. David also shares responsibility with Fran Adar of HORIBA for authoring the Molecular Spectroscopy Workbench, which appears regularly in Spectroscopy magazine. Prior to joining HORIBA, David was a Senior Researcher at the University of Pittsburgh from 2009 to early 2011 working on UV resonance Raman spectroscopy of explosives. He was the Principal Materials Scientist at ChemImage from 2002 to 2008. David was a research scientist and Raman spectroscopist at Kodak from 1985 to 2002 during which time he developed Polarization-Orientation Micro-Raman techniques for the characterization of solid state materials in general and photonic and microelectronic devices in particular. David received his M.S. degree in Chemistry from the University of Arizona under the direction of Prof. Jeanne E. Pemberton. His research involved the study of surface enhanced Raman scattering (SERS) and its dependence on electrode kinetics.

Short Biography

Andrey Krayev

Andrey Krayev received the Graduate degree from the Moscow Institute of Physics and Technology, in 1991. In 2001, he started to use SPM, when working as an application scientist for QPT, Inc. Since 2008, he has been a CTO at AIST-NT, Inc. He is actively involved in development of TERS technique and its implementation for real world application. After acquisition of AIST-NT technology by HORIBA in July of 2017, Andrey holds the position of the US AFM-Raman product manager for Horiba Scientific. He continues active development of TERS-related applications for advanced characterization of 2D materials and beyond.