V. Vibrational Spectroscopy in Materials Science

  • Vibrational spectroscopy gives useful information on geometry of molecules and symmetry groups of crystalline solid state systems. It also provides important electronic parameters such as derivatives of dipole moment and of polarizabilities of different order. Vibrational spectra (IR and Raman) are considered to be fingerprints of a given system, which allow its qualitative and often quantitative identification.
  • SERS and SERRS are two modifications of a surface-enhanced (inelastic) Raman scattering spectroscopy. In my Ph.D. and M.Sc. thesis I extended theoretical knowledge of these complex photochemical phenomena, and I proposed different applications for SERS and SERRS.
  • Our investigations revealed that:

(i) factors missing from enhenacement are different in the SERRS specra for different bands. The electromagnetic (surface plasmon) enhancement factors are quenched in the SERRS spectra for these bands, which are strongly surface-plasmon enhanced in the SERS spectra (Grochala W, Bukowska J, ”The components of relative enhancement factors in SERS and SERRS of murexide adsorbed at silver electrode“, unpublished);
(ii) the charge-transfer (chemical) enhancement factor is quenched in the SERRS spectra (see paper above); quenching is connected with redox processes occuring at the metal surface, and with competition of several paths of the excited state relaxation;
(iii) there are at least two main types of active surface sites responsible for the chemical enhancement; one of these types may be deactivated by applying large negative potentials to the silver electrode (VIB SPECTROSC 17 (2): 145-154 1998);
(iv) charge-transfer enhancement coefficients do not reach values as large as 1000 for R6G dye, as it was suggested in the literature (J RAMAN SPECTROSC 29 (8): 681-685 1998).

  • SERRS may be applied to study copper (VIB SPECTROSC 16 (1): 21-29 1998), copper oxide (J RAMAN SPECTROSC 29 (5): 431-435 1998) and gold surfaces (Grochala W, Piela P, Bukowska J, Wrona P, ”Characterization of Au surface optimized for use as a substrate for SERS”, unpublished), surfaces of amorphous catalytically active Cu-Zr alloys (MAT SCI ENG A-STRUCT 267 (2): 235-239 1999), and to investigate in-situ formation of conducting polymers (SYNTHETIC MET 89 (1): 29-37 1997).

At present I use spectroscopy (NMR, ESR, electronic absorption and reflection, IR absorption, Raman scattering, XPS, ESCA, XANES) and other techniques (including e.g. SQUID, XRD, MicroWave Cavity Perturbation) exclusively as a tool to determine fundamental properties of materials.