Abstract
We present the results of a Raman study of optical phonons in CuS nanocrystals (NCs) with a low areal density fabricated through the Langmuir–Blodgett technology on nanopatterned Au nanocluster arrays using a combination of surface- and interference-enhanced Raman scattering (SERS and IERS, respectively). Micro-Raman spectra of one monolayer of CuS NCs deposited on a bare Si substrate reveal only features corresponding to crystalline Si. However, a new relatively strong peak occurs in the Raman spectrum of CuS NCs on Au nanocluster arrays at 474 cm−1. This feature is related to the optical phonon mode in CuS NCs and manifests the SERS effect. For CuS NCs deposited on a SiO2 layer this phonon mode is also observed due to the IERS effect. Its intensity changes periodically with increasing SiO2 layer thickness for different laser excitation lines and is enhanced by a factor of about 30. CuS NCs formed on Au nanocluster arrays fabricated on IERS substrates combine the advantages of SERS and IERS and demonstrate stronger SERS enhancement allowing for the observation of Raman signals from CuS NCs with an ultra-low areal density.
Highlights
Investigations of Raman scattering in nanostuctures such as nanocrystals (NCs) are limited by a low Raman cross-section because of the very low scattering volume of the nanostructures.Surface-enhanced Raman spectroscopy (SERS) taking advantage of plasmonics leads to a remarkable increase of the Raman sensitivity as shown for several semiconductor NC types [1,2,3,4,5,6,7,8,9,10,11,12,13].Beilstein J
A pronounced 104-fold SERS enhancement by surface optical phonons was observed for ZnO NCs excited in resonance with localised surface plasmon in Ag nanoclusters deposited on ZnO NCs and out of the resonance [10,11]
These two issues make CuS NCs an attractive model system for SERS investigations of inorganic analytes. As it was demonstrated in [18], extremely thin absorbing coatings deposited on an antireflection layer exhibit interference-enhanced Raman scattering (IERS) providing an alternative opportunity to enhance the Raman response by phonons in absorbates
Summary
Investigations of Raman scattering in nanostuctures such as nanocrystals (NCs) are limited by a low Raman cross-section because of the very low scattering volume of the nanostructures.Surface-enhanced Raman spectroscopy (SERS) taking advantage of plasmonics leads to a remarkable increase of the Raman sensitivity as shown for several semiconductor NC types [1,2,3,4,5,6,7,8,9,10,11,12,13].Beilstein J. The first report on the observation of the SERS effect by optical phonons in CuS NCs on ordered arrays of Au nanoclusters fabricated in a nanolithography process was published recently [13].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
