Monitoring the charge-transfer process in a Nd-doped semiconductor based on photoluminescence and SERS technology

Surface-enhanced Raman scattering (SERS) and photoluminescence (PL) are important photoexcitation spectroscopy techniques; however, understanding how to analyze and modulate the relationship between SERS and PL is rather important for enhancing SERS, having a great effect on practical applications. In this work, a charge-transfer (CT) mechanism is proposed to investigate the change and relationships between SERS and PL. Analyzing the change in PL and SERS before and after the adsorption of the probe molecules on Nd-doped ZnO indicates that the unique optical characteristics of Nd3+ ions increase the SERS signal. On the other hand, the observed SERS can be used to explain the cause of PL background reduction. This study demonstrates that modulating the interaction between the probe molecules and the substrate can not only enhance Raman scattering but also reduce the SERS background. Our work also provides a guideline for the investigation of CT as well as a new method for exploring fluorescence quenching. Sensors that use laser light scattering to detect molecular-scale changes to samples can be improved with a new substrate that naturally reduces background interference. Surface-enhanced Raman spectroscopy (SERS) setups typically use a combination of metal nanoparticles and fluorescent probes to capture vibrational signals from biomolecules including DNA. Ming Gao from Jilin Normal University in Siping, China, and colleagues now report a technique to keep probe emissions from interfering with SERS signals. To accomplish this, the team synthesized a neodymium-doped zinc oxide spiky nanostructures substrate. Spectroscopic measurements revealed that neodymium’s electronic properties enabled it to transfer photoexcited electrons to the probes. This charge transfer reduced the probe’s fluorescent intensity and simultaneously enhanced SERS emissions beyond that available on pure zinc oxide surfaces. This study provides a new way to naturally eliminate the SERS fluorescence background by doping with Nd ions. These fundamental discussions here provide a path to enhance Raman scattering and reduce the SERS background and a guideline for the investigation of CT and a new method for exploring fluorescence quenching.