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Photo-Induced Enhanced Raman Spectroscopy (PIERS) is a new surface enhanced Raman spectroscopy (SERS) modality with an order-of-magnitude Raman signal enhancement of adsorbed analytes over that of typical SERS substrates. Despite the impressive PIERS enhancement factors and explosion in recent demonstrations of its utility, the detailed enhancement mechanism remains undetermined. Using a range of optical and X-ray spectroscopies, supported by density functional theory calculations, we elucidate the chemical and atomic-scale mechanism behind the PIERS enhancement. Stable PIERS substrates with enhancement factors of 10^6 were fabricated using self-organized hexagonal arrays of TiO2 nanotubes that were defect-engineered via annealing in inert atmospheres, and silver nanoparticles were deposited by magnetron sputtering and subsequent thermal dewetting. We identified the key source of the enhancement of PIERS vs. SERS in these structures as an increase in the Raman polarizability of the adsorbed probe molecule upon photo-induced charge transfer. A balance between crystallinity, which enhances charge transfer due to higher electron mobility in anatase-rutile heterostructures but decreases visible light absorption, and oxygen vacancy defects, which increase visible light absorption and photo-induced electron transfers, was critical to achieve high PIERS enhancements.
The ability to generate, amplify, mix, and modulate sound with no harmonic distortion in a passive opto-acoustic device would revolutionize the field of acoustics. The photo-thermo-acoustic (PTA) effect allows to transduce light into sound without an
The graphene-enhanced Raman scattering of Rhodamine 6G molecules on pristine, fluorinated and 4-nitrophenyl functionalized graphene substrates was studied. The uniformity of the Raman signal enhancement was studied by making large Raman maps. The rel
Polycrystalline ceramic samples and a single crystal of EuTiO3 have been investigated by Raman spectroscopy in the temperature range 80-300 K. Although synchrotron XRD data clearly indicated the cubic to tetragonal phase transition around 282 K, no m
We synthesized three-dimensional nanoporous graphene films by a chemical vapor deposition method with nanoporous copper as a catalytic substrate. The resulting nanoporous graphene has the same average pore size as the underlying copper substrate. Our
Celitement is a new type of cement that is based on hydraulic calcium-hydrosilicate (hCHS) that possesses a potential for minimizing the ratio C/S from above 3 in OPC down to 1, which significantly reduces the amount of CO$_2$ released during process