The observation of high order overtones and combinations in the SERRS spectra of a perylene dye spin coated onto silver island films

Abstract

The intensity of high harmonics and the background observed in the SERRS spectra of the bis(4-chlorbenzylimido)perylene (CLPTCD), spin-coated onto silver nanostructures are discussed. The SERRS spectra of an Ag island film spin coated with 50 microL of a 8.7 x 10(-7) M of CLPTCD in CH2Cl2 excited at 514.5 nm show signals from the first to the third overtones and combinations of fundamental vibrational modes observed between 1200 and 1600 cm(-1). SERRS spectra were obtained where 2nd overtones were seen with relative intensity equal to that of the 1st overtones and in other SERRS spectra the 3rd overtones were more intense than the 2nd overtones. These varying intensity patterns are seen at submonolayer coverage where there is a breakdown of statistical average, and the spatial distribution of enhancement factors becomes evident. The apparent correlation between the background intensity profile and the enhancement of the overtones and combinations is also discussed.

Understanding the Reaction Chemistry of 2,2′:5′,2″-Terthiophene Films with Vapor-Deposited Ag, Al, and Ca

“…These high frequency bands are thus assigned to overtones and combinations as a result of the surface-enhanced Raman (SERS) effect of ultrathin films (1.5 nm) in the near-surface region. Although overtone and combination bands have not been previously reported for α-3T thin films, the observation of overtones and combination bands associated with SERS has been extensively studied and observed for many organic thin film systems. − As shown in Table , the frequencies of these combination bands are shifted in frequency by the same amount; this shift is likely due to the fact that the SERS effect for the subpopulation of α-3T molecules very near the Ag surface slightly alters the frequencies of the fundamentals, thereby changing the frequencies of the overtone and combination bands.…”

Plasmon-Enhanced Fluorescence and Spectral Modification in SHINEF

“…10,11 For physisorbed molecules and submonolayer surface coverage the plasmon effects can be clearly captured in the far field scattering. 12 In SHINEF (or SEF, in general) the molecule is about 10 nm away from the metal surface, and the spectral modification is almost entirely due to the plasmonic modification of the observed enhanced spectrum.…”

“…Correspondingly, the far field scattering of electromagnetically enhanced SERS spectrum will contain the information that sheds light on these molecule–nanostructure interactions. The spectral modification in SERS due to the properties of the far field scattering itself is difficult to separate in the observed SERS spectra, although it has been identified by several groups. , For physisorbed molecules and submonolayer surface coverage the plasmon effects can be clearly captured in the far field scattering . In SHINEF (or SEF, in general) the molecule is about 10 nm away from the metal surface, and the spectral modification is almost entirely due to the plasmonic modification of the observed enhanced spectrum.…”

Metal—Organic Semiconductor Nanostructures for Surface-Enhanced Raman Scattering

“…2a, the UV-Vis absorption spectrum of the 6 nm Ag PVD film is characteristic of a plasmon of the nanostructures in Ag island films with a broad distribution of AgNPs in terms of size and shape with a tail due to AgNP aggregates. 26 The UV-Vis spectrum of the FePc presents the B band at lower wavelengths and the Q band at higher wavelengths, which are assigned to the HOMO!LUMO electronic transitions (p electrons). 27 The characteristic UV-Vis absorption spectra for PVD films of PTCDs (Fig.…”