A systematic spectral analysis was presented for bishemicyanine dyes(Hsd and D2)and monohemicyanine dyes(Hs and DSMI).The bishemicyanine dyes displayed long emission wavelengths,large Stokes shifts,low background quan...A systematic spectral analysis was presented for bishemicyanine dyes(Hsd and D2)and monohemicyanine dyes(Hs and DSMI).The bishemicyanine dyes displayed long emission wavelengths,large Stokes shifts,low background quantum yields in aqueous solutions and high sensitivity in viscous environments.Better understanding of the structure-property relationships could benefit the design of improved dyes.Computational studies on these dyes revealed the three conjugated forms of bishemicyanines are in equilibrium due to two positive charges and a branched bulk substituent.Bishemicyanines possessed obviously lower rotating energy barrier of C-C bond rotation compared to the monohemicyanine dyes.Moreover,the synergetic effects of the rotation about theφ4 bond,φ5 bond andφ7 bond of the bishemicyanines(Hsd and D2)lead to lower fluorescence quantum yields in a free state and larger fluorescence quantum yield enhancements in viscous environment compared to that of monohemicyanine dyes(Hs and DSMI).The results demonstrate a foundation for interpretation of the behavior of the dyes,thus providing guidelines for future of new bishemicyanine fluorophores with specific applications.展开更多
The growth parameters affecting the deposition of self-assembled InAs quantum dots （QDs） on GaAs substrate by low-pressure metal-organic chemical vapor deposition （MOCVD） are reported. The low-density InAs QDs （-...The growth parameters affecting the deposition of self-assembled InAs quantum dots （QDs） on GaAs substrate by low-pressure metal-organic chemical vapor deposition （MOCVD） are reported. The low-density InAs QDs （- 5 × 10^8cm^-2） are achieved using high growth temperature and low InAs coverage. Photoluminescence （PL） measurements show the good optical quality of low-density QDs. At room temperature, the ground state peak wavelength of PL spectrum and full-width at half-maximum （FWHM） are 1361 nm and 23 meV （35 nm）, respectively, which are obtained as the GaAs capping layer grown using triethylgallium （TEG） and tertiallybutylarsine （TBA）. The PL spectra exhibit three emission peaks at 1361, 1280, and 1204 nm, which correspond to the ground state, the first excited state, and the second excited state of the ODs, respectively.展开更多
基金financially supported by the National Natural Science Foundation of China(No.21606118)the State Key Laboratory of Fine Chemicals(No.KF1614)。
文摘A systematic spectral analysis was presented for bishemicyanine dyes(Hsd and D2)and monohemicyanine dyes(Hs and DSMI).The bishemicyanine dyes displayed long emission wavelengths,large Stokes shifts,low background quantum yields in aqueous solutions and high sensitivity in viscous environments.Better understanding of the structure-property relationships could benefit the design of improved dyes.Computational studies on these dyes revealed the three conjugated forms of bishemicyanines are in equilibrium due to two positive charges and a branched bulk substituent.Bishemicyanines possessed obviously lower rotating energy barrier of C-C bond rotation compared to the monohemicyanine dyes.Moreover,the synergetic effects of the rotation about theφ4 bond,φ5 bond andφ7 bond of the bishemicyanines(Hsd and D2)lead to lower fluorescence quantum yields in a free state and larger fluorescence quantum yield enhancements in viscous environment compared to that of monohemicyanine dyes(Hs and DSMI).The results demonstrate a foundation for interpretation of the behavior of the dyes,thus providing guidelines for future of new bishemicyanine fluorophores with specific applications.
文摘The growth parameters affecting the deposition of self-assembled InAs quantum dots （QDs） on GaAs substrate by low-pressure metal-organic chemical vapor deposition （MOCVD） are reported. The low-density InAs QDs （- 5 × 10^8cm^-2） are achieved using high growth temperature and low InAs coverage. Photoluminescence （PL） measurements show the good optical quality of low-density QDs. At room temperature, the ground state peak wavelength of PL spectrum and full-width at half-maximum （FWHM） are 1361 nm and 23 meV （35 nm）, respectively, which are obtained as the GaAs capping layer grown using triethylgallium （TEG） and tertiallybutylarsine （TBA）. The PL spectra exhibit three emission peaks at 1361, 1280, and 1204 nm, which correspond to the ground state, the first excited state, and the second excited state of the ODs, respectively.
