Raman Spectroscopy
The HORIBA LabRAM HR confocal Raman microscope previously available at the nmRC
Raman Spectroscopy at a glance
Raman spectroscopy is a non-invasive optical technique used to determine the chemical identity and state of a sample by its unique vibrational (molecular) modes. Inelastic (loss or gain of energy) scattering of light from the sample is measured, with distinct shifts in the energy of the scattered photons being representative of the sample chemistry.
Applications
- Vibrational spectra of substrate chemistry
- Confocal component mapping and depth profiling
- UV-Visible-IR excitation analysis
- Temperature and time dependent chemical and physical state change identification
- Ambient or controlled environment analysis
How does Raman work?
Raman spectroscopy and microscopy is a uniquely sensitive analytical technique that is non-invasive in nature. It can rapidly provide quantifiable identification of bulk and surface species with exceptional resolution. The technique measures the interaction between a monochromatic light source and the vibrational (and other low-frequency) modes of the molecular systems being analysed.
A given molecular vibration can be excited by a certain frequency of incident light to a higher virtual energy state. This higher energy state will almost always relax again to a lower energy state. While normally this occurs elastically (to its original energy state as Rayleigh scattering) it may also occur inelastically. This represents relaxation to a different vibrational energy level, generating the release of a photon with an altered frequency to that of the incident photon.
This change in frequency is the Raman shift, and can be recorded and plotted against the scattered light intensity. Therefore Raman scattering gives rise to reductions or gains in light frequencies that correspond very sensitively to the molecular structure and state of the material being analysed. Solving these spectra allows characterisation of the chemical and physical state of a material.
Our Raman Spectroscopy Facilities
HORIBA LabRam Odyssey Raman Microscope
- Conventional upright microscope geometry.
- Excitation wavelengths available: 325, 405, 532, 660 and 785 nm.
- Gratings available: 150, 300, 600, 1200, 1800 and 2400 lines/mm (depending on configuration).
- Objectives available: 5x, 10x, 40x, 50x and 100x (depending on configuration).
- imaging system for sub-micron to macro-scale mapping.
- software module and holder for high throughput screening using traditional well plates and related regular array sample geometries.
- software module for automated location, characterisation and Raman analysis of particles.
HORIBA XploRA INV Raman Microscope
- Inverted microscope geometry suitable for 'in-situ' analysis and biological samples.
- Excitation wavelength available: 785nm.
- Gratings available: 600, 1200, 1800 and 2400 lines/mm (configuration dependent).
- Objectives available: 10x, 20x and 100x.
HORIBA LabRam HR Evo Nano (DCI-TERS)
Scanning probe microscope coupled to a Raman microscope enabling tip-enhanced Raman spectroscopy (TERS) and co-localised AFM-Raman.
- Conventional upright microscope geometry.
- Excitation wavelengths available: 532, 633 and 785 nm.
- Gratings available: 150, 300, 600, 1200, 1800 and 2400 lines/mm.
- Objectives available: 5x, 10x, 50x, and 100x.
- Controllable confocality for standard or high spatial resolution imaging.
- Motorised half-wave and analyser plates for polarised Raman measurements.
- (ULF) Raman module allowing measurement in the sub-50 cm-¹ region.
- Imaging modes include AFM (contact, semi-contact, non-contact), KPFM, SCM, EFM, PFM, cAFM, LFM, FMM, MFM, STM and nanolithography.
- Dual optical access from the side and below for reflectance and transmission TERS measurements.
- Protective enclosure for environmental control.
- Sample and cantilever holders for variable temperature analysis in air (-50 to +300 oC) and liquids (ambient to +60 oC).
- Electrochemical cell for ecTERS.
Publications of Interest
- , T., Biskupek, J., Li, Z. Y., Rance, G. A., Botos, A., Fogarty, R. M., Bourne, R. A., Yuan, J., Lovelock, K. R. J., Thompson, P., Fay, M. W., Kaiser, U., Chamberlain, T. W. & Khlobystov, A. N., Nanoscale, 9, 14385–14394 (2017).
- , Walker, K. E., Rance, G. A., Pekker, Á., Tóháti, H. M., Fay, M. W., Lodge, R. W., Stoppiello, C. T., Kamarás, K. & Khlobystov, A. N., Small Methods, 1, 1700184 (2017).
- , Jordan, J. W., Lowe, G. A., McSweeney, R. L., Stoppiello, C. T., Lodge, R. W., Skowron, S. T., Biskupek, J., Rance, G. A., Kaiser, U., Walsh, D. A., Newton, G. N. & Khlobystov, A. N., Advanced Materials, 31, 1904182 (2019).
- , Clément, P., Xu, X., Stoppiello, C. T., Rance, G. A., Attanzio, A., O’Shea, J. N., Temperton, R. H., Khlobystov, A. N., Lovelock, K. R. J., Seymour, J. M., Fogarty, R. M., Baker, A., Bourne, R. A., Hall, B., Chamberlain, T. W. & Palma, M., Angewandte Chemie International Edition, 58, 9928–9932 (2019).
- , Sen, S., Goodwin, S. E., Barbará, P. V., Rance, G. A., Wales, D., Cameron, J. M., Sans, V., Mamlouk, M., Scott, K. & Walsh, D. A., ACS Applied Polymer Materials, 3, 200–208 (2021).