Raman Under Liquid Nitrogen (RUN)

22nd International Conference on Spectral Line Shapes

Compton, R.N.^1 ; Hammer, N.I.^2

Departments of Physics and Chemistry, University of Tennessee, Knoxville

TN

37996, United States^1

Department of Chemistry and Biochemistry, University of Mississippi, PO Box 1848, University

MS

38677, United States^2

关键词: Combination of lasers;    Energy conformers;    Higher resolution;    Lattice modes;    Nitrogen gas;    Raman peak;    Vibrational cooling;    Wavelength calibration;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/548/1/012017/pdf
DOI  :  10.1088/1742-6596/548/1/012017

来源: IOP

【 摘 要 】

The recording of Raman spectra for many molecules in air at room temperature is difficult or impossible as a result of sample degradation which is due to a combination of laser heating and oxidation. Often nitrogen gas is applied over the sample in an attempt to reduce oxidation. Also, the samples are sometimes cooled to reduce ro-vibrational "hot bands" and enhance the spectra. We have found great utility in recording Raman spectroscopy of samples under liquid nitrogen, a technique we call RUN. The RUN spectra show much higher resolution as a result of ro-vibrational cooling and in some cases cooling produces only the lowest energy conformer of the molecular ensemble further simplifying the spectra. A very sharp Raman peak at 2327.0 cm-1, due to liquid nitrogen, also serves as a convenient wavelength calibration. We also demonstrate the ability to clearly delineate the lattice modes for naphthalene and benzene crystals.