Surface‐enhanced resonance Raman and hyper‐Raman spectroscopy of water‐soluble substituted stilbene and distyrylbenzene chromophores

Abstract

Surface-enhanced Raman spectra (SERS) are presented for two water-soluble, donor-donor-or donor-acceptor-substituted phenylene vinylene derivatives adsorbed on the surfaces of colloidal silver nanoparticles. The normally water-insoluble, substituted stilbene and distyrylbenzene chromophores have been modified by attaching trimethylammoniumalkyl chains to the amino donor group, creating both aqueous solubility and a net positive charge that facilitates binding to citrate-or borohydride-reduced silver colloids. A symmetrically donor-substituted distyrylbenzene exhibits strong electronically pre-resonant SERS spectra that are not highly dependent on excitation wavelength and are qualitatively similar to the solution-phase resonance Raman (RR) spectra. A donor-acceptor-substituted stilbene exhibits weaker SERS enhancement despite being fully electronically resonant. The spectra vary considerably with excitation wavelength and show new lines not present in the solution-phase spectra, which are attributed to a photoproduct formed on the surface. Two-photon resonant hyper-Raman spectra are also presented for the donor-acceptor stilbene, both with and without surface enhancement.

SERRS and visible extinction spectroscopy of copper chlorophyllin on silver colloids as a function of pH

“…Numerous chemical species have been investigated, such as: organic compounds [17,[20][21][22][23][24][25][26][27][28], acids and bases [18,29,30], dyes [31][32][33][34], porphyrin-related compounds and biomolecules [9,19,[35][36][37][38]. Hildebrandt and Spiro studied Cu(II) chlorin e 6 adsorbed on Ag and Au colloids using SERRS to understand its adsorption and assign vibrational modes [9].…”

Hyper-Raman scattering enhanced by anisotropic dimer plasmons on artificial nanostructures

“…In a similar manner of SERS, surface-enhanced hyper-Raman scattering ͑SEHRS͒ has been reported in metal colloid or roughed electrode sytems. 14,[18][19][20][21] Then, fabrication of welldefined hot spots is awaited for further development of hyper-Raman spectroscopy.…”

Raman spectroscopy at the beginning of the twenty‐first century

“…From the dominating in-plane modes, the authors conclude on a tilted orientation of the triazole molecule. A very interesting contribution by Leng et al 16 describes the resonance Raman and resonance hyper-Raman investigations of two types of 'push-pull' compounds -designated donor-donor or donor-acceptor substituted phenylene vinylene derivatives -and compares these spectra to their surface-enhanced counterparts. The authors carefully report the effects of metal colloids on these linear and non-linear spectra and compare the linear and non-linear scattering to each other.…”