pevné látky   biofyzika                 
Náš ústav se účastní projektu


Středoevropský technologický institut

  Ústavy fyziky jsou součástí Přírodovědecké fakulty Masarykovy univerzity v Brně. Cesky   English  

Plasmonic enhanced Raman spectroscopy

The relatively low cross-section of Raman scattering prevents routine application of Raman spectroscopy in cases where need arises to characterize solid state samples containing structures with thickness in the monolayer range or biomolecular samples in the range of physiological concentrations. Apart from resonant enhancement coming from inclusion of electronic transitions, the scattering efficiency can be augmented in these cases using substrates with metallic nanostructures.

Raman enhancement is coming through amplification of probing light in the near field when suitably coupled to the electron plasma oscillations in the metallic nanostructures. Our focus lies in mutual tuning of the probing light and the nanostructures for optimal enhancement.

key techniques:
  • Resonant Raman spectroscopy (RRS)
      continuous wavelength tunable excitation
  • SERS in colloids
      Au spherical NP, Ag multistep prism NP
      Ag decahedrons, nanostars
      Au-Ag core-shell NP
  • ATR-Raman
      surface sensitive Raman modality
      both for solid samples and in microfludic setting
  • SPM+Raman
      STM-TERS with on-site etched Au/Ag tips
      high-resolution AFM

equipment:Renishaw inVia
Fianium WhiteLase SC450 High-Power Supercontinuum
NT-MDT Solar II + Ntegra spectra

contact: Dusan Hemzal, Filip Munz
hemzal at physics.muni.cz
students: Vit Pavelka (SERS, nanoparticles), Petr Steindl (FDTD)
David Linhart (TERS)
cooperation: TIRE group
Karel Kubicek (biophysics), Jan Hrbac (SERS substrates, electrochemistry)
external: Petr Klapetek (Metrologuical insittute; AFM, FDTD simulations), Vit Jan (Brno University of technology; SEM+EDX, AAO substrates), Anna Tycova (Inst. analytical chemistry, Czech Academy of sciences; nanoparticles)

papers: Pavelka V., Hemzal D., Hrbac J.: Complex evaluation of Raman spectra using morphological filtering: algorithms, software implementation and experimental verification of baseline correction, peak recognition and cosmic ray removal in SERS spectra of designer drugs, J. Raman Spectroscopy (2022), https://doi.org/10.1002/jrs.6448

Trachioti M.G., Hemzal D., Hrbac J., Prodromidis M.I.: Generation of graphite nanomaterials from pencil leads with the aid of a 3D positioning sparking device: Application to the voltammetric determination of nitroaromatic explosives, Sens. Actuator B-Chem. 310, 127871 (2020), link

Halouzka V., Halouzkova B., Jirovsky D., Hemzal D., et al: Copper nanowire coated carbon fibers as efficient substrates for detecting designer drugs using SERS, Talanta 165(4), 384-390 (2017), link

Sharma V., Hynek D., Trnkova L., Hemzal D., et al: Electrochemical determination of adenine using a glassy carbon electrode modified with graphene oxide and polyaniline, Microchim Acta 183(4), 1299-1306 (2016), link

case studies:

Depth scan across ATR-Raman spectra with 10 mW excitation at 532 nm of Ag chip covered with (presumably a monolayer of) brilliant cresyl blue from 20 min soaking in 1 mM solution. The step between two subsequent spectra is 0.025 mm; x20 LWD objective with NA=0.4 was used to measure the spectra with accumulation of 1 s. (2020)

Absorbance of citrate capped silver nanoprisms, as prepared and after 4-step centrifugation (FWHM 187 nm). The inset shows for comparison result of rate-zonal centrifugation; the bottom unfractionated centrifuggate is equivalent to the 4-step centrifugation. (2020)

STM map of TIRE-immobilised citrate covered Ag nanoparticle(s) over PVD Au@SiO2 substrate using on-site etched Au tip; the scale bar is 5 nm. (2017)

Reflectivity mapping of on-site etched Au STM tip in contact with Au@BK7 substrate at room ambient; the scale bar is 1 um. The inset shows higher resolution measurement overlayed with Raman map revealing the TERS hot spot when using 633 nm excitation. (2017)

AFM phase image (air ambient) of Rtt103 protein CTD ineracting domain loaded via TIRE over Au/SiO2 substrate. Rtt103-CID is a predominantly helical peptide, some of the helices are resolved within the adsorbed molecules. The expected 2km4 structure of the peptide from pdb.org is overlayed (enlarged approx. 10x for better readability). (2016)

Tunable excitation SERRS spectra of 1uM solution of rhodamine 6G in Ag NP colloid with absorption maximum at 450 nm. The wavelengths of the excitating laser are given in legend, the vertical axes share absolute units (normalised to 50 s acquisition at 100 uW). The inset shows conventional Raman spectrum of 100 uM R6G (acquisition 100 s by 30 mW at 633 nm). As the optical path for both samples was same, the SERRS enhancement can be easily calculated, close to EF=106 at 1510/cm R6G peak. (2015)

Turkevich method-synthetized Au NPs over graphite substrate. Using the advanced versions of the protocol, particles become practically monodisperse. (2014)

Excited plasmon in ATR-Raman as monitored in outgoing beam past the ATR ctystal: when changing continuously the wavelength of the excitation laser (shown 490-630 nm in 20 nm steps), the plasmonic dip follows the optimal resonance by shifting in incident angle and changing width. The sharpness of the SPR dip is due to using Ag chip and focusing probes. (2020)

Characterization of silver colloids: maturing of decahedron AgNPs and comparison of their final state (FWHM 29 nm) to normalized absorbance of washed silver nanoprisms and Lee-Meisel type Ag colloid. (2020)

On-site etched Au STM tips with controlled angle of apex for tuning the plasmonic resonance. (2019)

Room ambient STM map of PVD Au@BK7 substrate using on-site etched Au tip with high resolution map of a selected region included. The scale bar is 5 nm. (2017)

Dried ambient STM map of TIRE-immobilised Rtt103 protein over atomically resolved PVD Au@BK7 substrate using on-site etched Au tip; the scale bar is 1 nm. (2016)

Ag NP mixture over AAO substrate. The shape (conjugately with size) of the NP is controlled by presence of halides during synthesis. Absorption maxima (ranging in general from VIS to IR) for the stocks shown in the bottom are given in the inset. (2015)

The apex of a nose-type AFM tip before and after PVD coating with gold. (2015)

AFM scan (air ambient) of mica deposited DNA; immobilisation via Mg2+. (2014)


(c) Ústav fyziky kondenzovaných látek                             sers.shtml změněn 20.09.2022