RESUMO
Strain plays an important role for the optical properties of monolayer transition metal dichalcogenides (TMDCs). Here, we investigate strain effects in a monolayer MoSe2 sample with a large bubble region using µ-Raman, second harmonic generation (SHG), µ-photoluminescence and magneto µ-photoluminescence at low temperature. Remarkably, our results reveal the presence of a non-uniform strain field and the observation of emission peaks at lower energies which are the signatures of exciton and trion quasiparticles red-shifted by strain effects in the bubble region, in agreement with our theoretical predictions. Furthermore, we have observed that the emission in the strained region decreases the trion binding energy and enhances the valley g-factors as compared to non-strained regions. Considering uniform biaxial strain effects within the unit cell of the TMDC monolayer (ML), our first principles calculations predict the observed enhancement of the exciton valley Zeeman effect. In addition, our results suggest that the exciton-trion fine structure plays an important role for the optical properties of strained TMDC ML. In summary, our study provides fundamental insights on the behaviour of excitons and trions in strained monolayer MoSe2 which are particularly relevant to properly characterize and understand the fine structure of excitonic complexes in strained TMDC systems/devices.
RESUMO
Most of the decisions made in planning treatment with implants rely on the clinician's assessment of the density of the jawbone. However, we know of only a few studies that have evaluated the clinicians' subjectivity and the objective quantitative methods. Our aim was to assess whether the characteristics of the bone seen on preoperative imaging are similar to the features faced during the operation. We collected data about 32 implant procedures done during the Specialisation Course for Implant Dentistry, Universidade de Ribeirão Preto, San Paulo. First, the clinicians evaluated the panoramic radiograph and computed tomographic scans preoperatively, classified the bone density according to the Lekholm and Zarb classification, and marked their subjective evaluation on a visual analogue scale. Postoperatively the surgeons filled out a questionnaire based on their subjective perceptions obtained during the insertion of the implants. Another examiner answered the same questionnaire after looking at the patient's images but without knowing the surgeon's results. There was a good correlation between the surgeons' preoperative classification of the type of bone and their tactile perception (p=0.000), and a good correlation between the surgeon's preoperative classification of the bone and the examiner's findings (p=0.000). We conclude that imaging is an important part of preoperative planning and can predict the quality of the bone when coupled with the opinion of a trained clinician, objective analysis, and standard classification of the bone.