For absorption linewidth inversion with wavelength modulation spectroscopy（WMS）, an optimized WMS spectral line fitting method was demonstrated to infer absorption linewidth effectively, and the analytical expressio...For absorption linewidth inversion with wavelength modulation spectroscopy（WMS）, an optimized WMS spectral line fitting method was demonstrated to infer absorption linewidth effectively, and the analytical expressions for relationships between Lorentzian linewidth and the separations of first harmonic peak-to-valley and second harmonic zero-crossing were deduced. The transition of CO_2 centered at 4991.25 cm^（-1） was used to verify the optimized spectral fitting method and the analytical expressions. Results showed that the optimized spectra fitting method was able to infer absorption accurately and compute more than 10 times faster than the commonly used numerical fitting procedure. The second harmonic zero-crossing separation method calculated an even 6 orders faster than the spectra fitting without losing any accuracy for Lorentzian dominated cases. Additionally, linewidth calculated through second harmonic zero-crossing was preferred for much smaller error than the first harmonic peak-to-valley separation method. The presented analytical expressions can also be used in on-line optical sensing applications, electron paramagnetic resonance, and further theoretical characterization of absorption lineshape.展开更多
The realization of colloidal alloy quantum dots(QDs)with narrow spectral linewidths requires minimization of the contributions of inhomogeneous and homogeneous broadening to the ensemble spectrum.Recently,there has be...The realization of colloidal alloy quantum dots(QDs)with narrow spectral linewidths requires minimization of the contributions of inhomogeneous and homogeneous broadening to the ensemble spectrum.Recently,there has been remarkable progress in eliminating the inhomogeneous contribution by controlling the size distribution of the QDs.However,considerable challenges remain in suppressing the homogeneous broadening,in terms of both intrinsic principles and rational synthetic routes.We find that ground-state exciton fine structure splitting and exciton-phonon coupling play a pivotal role in the homogeneous broadening mechanism.Here we demonstrate that the elimination of the lattice mismatch strain by using a coherent strain structure can decrease the light-heavy hole splitting,thus suppressing the asymmetric broadening of the emission on the high energy side.Besides,the improvement of the uniformity of the alloy by using a stepwise ion exchange strategy can weaken the exciton-longitudinal optical(LO)-phonon interactions,further minimizing the homogeneous broadening.As a result,the final alloy QD products exhibit a widely tunable blue emission wavelength(445-470 nm)with the narrowest ensemble photoluminescence full width at half maximum(FWHM)of 10.1-13.5 nm(or 58.4-75.3 meV).Our study provides a potential strategy for other semiconductor nanocrystals with ultranarrow spectral linewidths.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61505142)the Tianjin Natural Science Foundation(Grant No.16JCQNJC02100)
文摘For absorption linewidth inversion with wavelength modulation spectroscopy（WMS）, an optimized WMS spectral line fitting method was demonstrated to infer absorption linewidth effectively, and the analytical expressions for relationships between Lorentzian linewidth and the separations of first harmonic peak-to-valley and second harmonic zero-crossing were deduced. The transition of CO_2 centered at 4991.25 cm^（-1） was used to verify the optimized spectral fitting method and the analytical expressions. Results showed that the optimized spectra fitting method was able to infer absorption accurately and compute more than 10 times faster than the commonly used numerical fitting procedure. The second harmonic zero-crossing separation method calculated an even 6 orders faster than the spectra fitting without losing any accuracy for Lorentzian dominated cases. Additionally, linewidth calculated through second harmonic zero-crossing was preferred for much smaller error than the first harmonic peak-to-valley separation method. The presented analytical expressions can also be used in on-line optical sensing applications, electron paramagnetic resonance, and further theoretical characterization of absorption lineshape.
基金We gratefully acknowledge the financial support of the Natural Science Foundation of China(No.12174169)the Natural Science Foundation of Guangdong Province(Nos.2021A1515012292 and 2022A1515012448)+5 种基金the Scientific Research Foundation of the Higher Education Institutions of Guangdong Province(Nos.2019KCXTD012,2020ZDZX3034,2019KZDZX2008,and 2020ZDZX2055)the Natural Science Foundation of Jiangxi Province(Nos.20192ACBL21045 and 20181BBE50022)the Talent Project of Lingnan Normal University(Nos.ZL2021029 and ZL2021030)the Science and Technology Plan Project of Zhanjiang(Nos.2020B01085,2021A05233,2020A03003,and 2021A05042)the Young Innovative Talents Project of University of Guangdong Province(No.2018KQNCX153)the Yanling Outstanding Yong Teacher Training Program Funded Project of Lingnan Normal University(No.YL20200102).
文摘The realization of colloidal alloy quantum dots(QDs)with narrow spectral linewidths requires minimization of the contributions of inhomogeneous and homogeneous broadening to the ensemble spectrum.Recently,there has been remarkable progress in eliminating the inhomogeneous contribution by controlling the size distribution of the QDs.However,considerable challenges remain in suppressing the homogeneous broadening,in terms of both intrinsic principles and rational synthetic routes.We find that ground-state exciton fine structure splitting and exciton-phonon coupling play a pivotal role in the homogeneous broadening mechanism.Here we demonstrate that the elimination of the lattice mismatch strain by using a coherent strain structure can decrease the light-heavy hole splitting,thus suppressing the asymmetric broadening of the emission on the high energy side.Besides,the improvement of the uniformity of the alloy by using a stepwise ion exchange strategy can weaken the exciton-longitudinal optical(LO)-phonon interactions,further minimizing the homogeneous broadening.As a result,the final alloy QD products exhibit a widely tunable blue emission wavelength(445-470 nm)with the narrowest ensemble photoluminescence full width at half maximum(FWHM)of 10.1-13.5 nm(or 58.4-75.3 meV).Our study provides a potential strategy for other semiconductor nanocrystals with ultranarrow spectral linewidths.
