Materials with blue-shifted and enhanced emission exhibit extensive applications in information encryption,solar ultraviolet sensing and ink-free printing,however,preparing blue-shifted and enhanced emission from phot...Materials with blue-shifted and enhanced emission exhibit extensive applications in information encryption,solar ultraviolet sensing and ink-free printing,however,preparing blue-shifted and enhanced emission from photo-responsive material remains a significant challenge.Herein,we designed and synthesized successfully the photo-responsive ionic-bonded organic crystals(IOC)using tetraphenylethylene(TPE)-based multidentate imidazolium salt and sulfonic acid.Impressively,the discernible response of IOC to UV light is evidenced by a blue shift and an enhancement in dilute solution.Specifically,this has resulted in a significant increase in the absolute quantum yield,from 7.0%to 41.3%.This remarkable efficiency can be attributed to the cooperative effect that reduces non-radiative processes,the restriction of intermolecular motions(RIM)and the modulation of charge transfer(CT)behavior.This work first reports blue-shifted and enhanced emission from ionic crystal,providing a new strategy to achieve photochromic materials.展开更多
Theoretical calculations are performed to study the nature of the hydrogen bonds in complexes HCHO···HNO, HCOOH···HNO, HCHO···NH3, HCOOH···NH3, HCHO·...Theoretical calculations are performed to study the nature of the hydrogen bonds in complexes HCHO···HNO, HCOOH···HNO, HCHO···NH3, HCOOH···NH3, HCHO···NH2F and HCOOH···NH2F. The geomet- ric structures and vibrational frequencies of these six complexes at the MP2/6-31+G(d,p), MP2/6-311++G(d,p), B3LYP/6-31+G(d,p) and B3LYP/6-311++G(d,p) levels are calculated by standard and counterpoise-corrected methods, respectively. The results indicate that in complexes HCHO···HNO and HCOOH···HNO the N—H bond is strongly contracted and N—H···O blue-shifted hydrogen bonds are observed. While in complexes HCHO···NH3, HCOOH···NH3, HCHO···NH2F and HCOOH···NH2F, the N—H bond is elongated and N—H···O red-shifted hydrogen bonds are found. From the natural bond orbital analysis it can be seen that the X—H bond length in the X—H···Y hydrogen bond is controlled by a balance of four main factors in the opposite directions: hyperconjugation, electron density redistribu- tion, rehybridization and structural reorganization. Among them hyperconjugation has the effect of elongating the X—H bond, and the other three factors belong to the bond shortening effects. In complexes HCHO···HNO and HCOOH···HNO, the shortening effects dominate which lead to the blue shift of the N—H stretching frequencies. In complexes HCHO···NH3, HCOOH···NH3, HCHO···NH2F and HCOOH···NH2F where elongating effects are dominant, the N—H···O hydrogen bonds are red-shifted.展开更多
Ab initio quantum chemistry methods were applied to study the bifurcated bent hydrogen bonds Y…H2CZ(Z=O,S,Se)and Y…H2CZ2(Z=F,Cl,Br)(Y=Cl-,Br-)at the MP2/6-311++G(d,p)and MP2/6-311++G(2df,2p)levels.The results show t...Ab initio quantum chemistry methods were applied to study the bifurcated bent hydrogen bonds Y…H2CZ(Z=O,S,Se)and Y…H2CZ2(Z=F,Cl,Br)(Y=Cl-,Br-)at the MP2/6-311++G(d,p)and MP2/6-311++G(2df,2p)levels.The results show that in each complex there are two equivalent blue-shifted H-bonds Y…H—C,and that the interaction energies and blue shifts are large,the energy of each Y…H—C H-bond is 15-27 kJ/mol,andΔr(CH)=-0.1--0.5 pm andΔv(CH)=30-80 cm-1.The natural bond orbital analysis shows that these blue-shifted H-bonds are caused by three factors:large rehybridization;small direct intermolecular hyperconjugation and larger indirect intermolecular hy-perconjugation;large decrease of intramolecular hyperconjugation.The topological analysis of elec-tron density shows that in each complex there are three intermolecular critical points:there is one bond critical point between the acceptor atom Y and each hydrogen,and there is a ring critical point inside the tetragon YHCH,so these interactions are exactly H-bonding.展开更多
A theoretical study on the blue-shifted H-bond N-H…O and red-shifted H-bond O-H…O in the complex HNO…H2O2 was conducted by employment of both standard and counterpoise-corrected methods to calculate the geometric s...A theoretical study on the blue-shifted H-bond N-H…O and red-shifted H-bond O-H…O in the complex HNO…H2O2 was conducted by employment of both standard and counterpoise-corrected methods to calculate the geometric structures and vibrational frequencies at the MP2/6-31G（d）, MP2/6-31 ＋ G（d,p）, MP2/6-311 ＋ ＋ G（d,p）, B3LYP/6-31G（d）, B3LYP/6-31 ＋G（d,p） and B3LYP/6-311 ＋ ＋G（d,p） levels. In the H-bond N-H…O, the calculated blue shift of N-H stretching frequency is in the vicinity of 120 cm^-1 and this is indeed the largest theoretical estimate of a blue shift in the X-H…Y H-bond ever reported in the literature. From the natural bond orbital analysis, the red-shifted H-bond O-H…O can be explained on the basis of the dominant role of the hyperconjugation. For the blue-shifted H-bond N-H…O, the hyperconjugation was inhibited due to the existence of significant electron density redistribution effect, and the large blue shift of the N-H stretching frequency was prominently due to the rehybridization of spn N-H hybrid orbital.展开更多
Nano-Y_2O_3:Eu^(3+) powder was prepared by the homogeneous precipitation. With controlling the conditions of the reaction, nano powders with different grain size were obtained. It is found that the blue-shift phenomen...Nano-Y_2O_3:Eu^(3+) powder was prepared by the homogeneous precipitation. With controlling the conditions of the reaction, nano powders with different grain size were obtained. It is found that the blue-shift phenomena exist in the nano-Y2O3:Eu3+ emission spectra excited by X-ray. The wave lengths of the peak (5D0→7F2) are related with the grain size of the powder展开更多
Poly（3-（2-methoxyphenyl）thiophene） （PMP-Th） nanowires were fabricated using porous anodic alumina （PAA） as template through electrochemical polymerization by cyclic voltammetry. The control on the size of nano...Poly（3-（2-methoxyphenyl）thiophene） （PMP-Th） nanowires were fabricated using porous anodic alumina （PAA） as template through electrochemical polymerization by cyclic voltammetry. The control on the size of nanowires was confirmed by electron microscopy. The results indicated that the luminescence spectra of PMP-Th nanowires in PAA nanochannels were blue-shifted and emission intensity was enhanced compared to the emission of the PMP-Th film. Moreover, the luminescent spectra of PMP-Th nanowires were size dependent, which may result from the change in the degree of confinement of nanowires in PAA. F6rster energy transfer from PAA to PMP-Th molecules is considered to be responsible for the enhancement of luminescence from PMP-Th nanowires in PAA. The results show that the emission properties of polymers with nanostructures can be tuned by controlling their size.展开更多
In this study, two-section mode-locked semiconductor lasers with different numbers of quantum wells and different types of waveguide structures are made. Their ultrashort pulse features are presented. The spectral dyn...In this study, two-section mode-locked semiconductor lasers with different numbers of quantum wells and different types of waveguide structures are made. Their ultrashort pulse features are presented. The spectral dynamical behaviors in these lasers are studied in detail. In the simulation part, a two-band compressive-strained quantum well（QW） model is used to study thermally induced band-edge detuning in the amplifier and saturable absorber（SA）. A sudden blue shift in laser spectrum is expected by calculating the peak of the net gain. In the experiment part, the sudden blue shift in the emission spectrum is observed in triple QW samples under certain operating conditions but remains absent in single QW samples.Experimental results reveal that blue shift phenomenon is connected with the difference between currents in two sections.Additionally, a threshold current ratio for blue-shift is also demonstrated.展开更多
The optical properties of Silicon-doped InGaN and GaN grown on sapphire by MOCVD have been investigated by photoluminescence (PL) method. At room temperature, the band-gap peak of InGaN is 437.0 nm and its full width ...The optical properties of Silicon-doped InGaN and GaN grown on sapphire by MOCVD have been investigated by photoluminescence (PL) method. At room temperature, the band-gap peak of InGaN is 437.0 nm and its full width of half-maximum (FWHM) is about 14.3 nm. The band-gap peak and FWHM for GaN are 364.4 nm and 9.5 nm, respectively. By changing the temperature from 20 K to 293 K, it is found that the PL intensity of samples decreases but the FWHM broadens with the increasing of the temperature. GaN sample shows red-shift, InGaN sample shows red-blue-red-shift. The temperature dependence of peak energy shift is studied and explained.展开更多
The hydrogen bonding interaction of formic acid-, formaldehyde-, formylfluoride-nitrosyl hydride complexes was investigated by the density functional theory （DFT） and ab inito method in conjunction with 6-311＋＋G（...The hydrogen bonding interaction of formic acid-, formaldehyde-, formylfluoride-nitrosyl hydride complexes was investigated by the density functional theory （DFT） and ab inito method in conjunction with 6-311＋＋G（2d,2p） basis set. The geometries, vibrational frequencies and interaction energies of the complexes were calculated by both standard and CP-corrected methods respectively. Moreover, G3B3 method was employed to estimate the interaction energies. There are C--H…O, N--H…O, N--H…F blue-shifted H-bonds and red-shifted O----H…O H-bond in the complexes. Electron density redistribution and rehybridization contribute to the N--H and C--H blue shifts. All geometric reorganizations contribute to the N--H blue shifts and partial geometric reorganizations contribute to the C--H blue shifts. The geometric reorganizations of the complex C except ZH（5）-O（4）-C（1） contribute to the O----H red shift. For the N--H blue shifts, the effect of r（N--O） variation on the N--H blue shifts is larger than that of ZH-N-O variation. Rehybridization plays a dominant role in the degree of N--H blue shifts, whereas the electron density redistribution contributes more to the degree of C--H blue shifts than the other effects do.展开更多
The porous alumina have been prepared by anodization and an organic molecule 8-hydroxyquinoline aluminum (Alq3) has been impregnated in the pores. The morphology measured through atomic force microscopy shows that the...The porous alumina have been prepared by anodization and an organic molecule 8-hydroxyquinoline aluminum (Alq3) has been impregnated in the pores. The morphology measured through atomic force microscopy shows that the size of the pores is about 10 nm. A blue-shift photoluminescence of Alq3 in nanometer-sized hole is close to that of the monomers. The measured spectral characteristics demonstrate the limitation of the porous alumina to the emission of Alq3.展开更多
Mamyshev oscillators (MOs) exhibit the potential for generating high average power and ultrashort pulses. Herein,we construct an MO using flexible double-cladding ytterbium-fiber with a fusion-spliced-combiner pumped ...Mamyshev oscillators (MOs) exhibit the potential for generating high average power and ultrashort pulses. Herein,we construct an MO using flexible double-cladding ytterbium-fiber with a fusion-spliced-combiner pumped scheme.Consistent with the most reported research results, the offset filter separation significantly affects the pulse characteristics(spectrum, pulse duration, etc.). Notably, in comparison with red-shifting, blue-shifting the peak spectral emission of the grating filter relative to a constant central wavelength of the bandpass filter substantially enhances the laser output characteristics. This phenomenon, which has not been previously reported, results in an average power up to 2.23 W and a pulse duration as short as 49 fs. To our knowledge, this is the highest average power achieved in sub-50 fs pulse duration in the nonlinear polarization rotation-assisted mode-locked MO laser architecture. The presented technique offers unique scientific proof for developing ultrafast laser sources with higher average power and shorter pulse duration.展开更多
基金the Gansu Natural Science Foundation(No.21JR7RA076)LICP Cooperation Foundation for Young Scholars(No.HZJJ23-6)for financial support。
文摘Materials with blue-shifted and enhanced emission exhibit extensive applications in information encryption,solar ultraviolet sensing and ink-free printing,however,preparing blue-shifted and enhanced emission from photo-responsive material remains a significant challenge.Herein,we designed and synthesized successfully the photo-responsive ionic-bonded organic crystals(IOC)using tetraphenylethylene(TPE)-based multidentate imidazolium salt and sulfonic acid.Impressively,the discernible response of IOC to UV light is evidenced by a blue shift and an enhancement in dilute solution.Specifically,this has resulted in a significant increase in the absolute quantum yield,from 7.0%to 41.3%.This remarkable efficiency can be attributed to the cooperative effect that reduces non-radiative processes,the restriction of intermolecular motions(RIM)and the modulation of charge transfer(CT)behavior.This work first reports blue-shifted and enhanced emission from ionic crystal,providing a new strategy to achieve photochromic materials.
基金the National Natural Science Foundation of China(Grant No.20477043)Knowledge Innovation Program by Chinese Academy of Sciences(KJCX2-SW-H08)
文摘Theoretical calculations are performed to study the nature of the hydrogen bonds in complexes HCHO···HNO, HCOOH···HNO, HCHO···NH3, HCOOH···NH3, HCHO···NH2F and HCOOH···NH2F. The geomet- ric structures and vibrational frequencies of these six complexes at the MP2/6-31+G(d,p), MP2/6-311++G(d,p), B3LYP/6-31+G(d,p) and B3LYP/6-311++G(d,p) levels are calculated by standard and counterpoise-corrected methods, respectively. The results indicate that in complexes HCHO···HNO and HCOOH···HNO the N—H bond is strongly contracted and N—H···O blue-shifted hydrogen bonds are observed. While in complexes HCHO···NH3, HCOOH···NH3, HCHO···NH2F and HCOOH···NH2F, the N—H bond is elongated and N—H···O red-shifted hydrogen bonds are found. From the natural bond orbital analysis it can be seen that the X—H bond length in the X—H···Y hydrogen bond is controlled by a balance of four main factors in the opposite directions: hyperconjugation, electron density redistribu- tion, rehybridization and structural reorganization. Among them hyperconjugation has the effect of elongating the X—H bond, and the other three factors belong to the bond shortening effects. In complexes HCHO···HNO and HCOOH···HNO, the shortening effects dominate which lead to the blue shift of the N—H stretching frequencies. In complexes HCHO···NH3, HCOOH···NH3, HCHO···NH2F and HCOOH···NH2F where elongating effects are dominant, the N—H···O hydrogen bonds are red-shifted.
文摘Ab initio quantum chemistry methods were applied to study the bifurcated bent hydrogen bonds Y…H2CZ(Z=O,S,Se)and Y…H2CZ2(Z=F,Cl,Br)(Y=Cl-,Br-)at the MP2/6-311++G(d,p)and MP2/6-311++G(2df,2p)levels.The results show that in each complex there are two equivalent blue-shifted H-bonds Y…H—C,and that the interaction energies and blue shifts are large,the energy of each Y…H—C H-bond is 15-27 kJ/mol,andΔr(CH)=-0.1--0.5 pm andΔv(CH)=30-80 cm-1.The natural bond orbital analysis shows that these blue-shifted H-bonds are caused by three factors:large rehybridization;small direct intermolecular hyperconjugation and larger indirect intermolecular hy-perconjugation;large decrease of intramolecular hyperconjugation.The topological analysis of elec-tron density shows that in each complex there are three intermolecular critical points:there is one bond critical point between the acceptor atom Y and each hydrogen,and there is a ring critical point inside the tetragon YHCH,so these interactions are exactly H-bonding.
基金Project supported by the National Natural Science Foundation of China （No. G20477043） and Knowledge Creative Program of Chinese Academy of Sciences （No. KJCX2-SW-H08）.
文摘A theoretical study on the blue-shifted H-bond N-H…O and red-shifted H-bond O-H…O in the complex HNO…H2O2 was conducted by employment of both standard and counterpoise-corrected methods to calculate the geometric structures and vibrational frequencies at the MP2/6-31G（d）, MP2/6-31 ＋ G（d,p）, MP2/6-311 ＋ ＋ G（d,p）, B3LYP/6-31G（d）, B3LYP/6-31 ＋G（d,p） and B3LYP/6-311 ＋ ＋G（d,p） levels. In the H-bond N-H…O, the calculated blue shift of N-H stretching frequency is in the vicinity of 120 cm^-1 and this is indeed the largest theoretical estimate of a blue shift in the X-H…Y H-bond ever reported in the literature. From the natural bond orbital analysis, the red-shifted H-bond O-H…O can be explained on the basis of the dominant role of the hyperconjugation. For the blue-shifted H-bond N-H…O, the hyperconjugation was inhibited due to the existence of significant electron density redistribution effect, and the large blue shift of the N-H stretching frequency was prominently due to the rehybridization of spn N-H hybrid orbital.
文摘Nano-Y_2O_3:Eu^(3+) powder was prepared by the homogeneous precipitation. With controlling the conditions of the reaction, nano powders with different grain size were obtained. It is found that the blue-shift phenomena exist in the nano-Y2O3:Eu3+ emission spectra excited by X-ray. The wave lengths of the peak (5D0→7F2) are related with the grain size of the powder
文摘Poly（3-（2-methoxyphenyl）thiophene） （PMP-Th） nanowires were fabricated using porous anodic alumina （PAA） as template through electrochemical polymerization by cyclic voltammetry. The control on the size of nanowires was confirmed by electron microscopy. The results indicated that the luminescence spectra of PMP-Th nanowires in PAA nanochannels were blue-shifted and emission intensity was enhanced compared to the emission of the PMP-Th film. Moreover, the luminescent spectra of PMP-Th nanowires were size dependent, which may result from the change in the degree of confinement of nanowires in PAA. F6rster energy transfer from PAA to PMP-Th molecules is considered to be responsible for the enhancement of luminescence from PMP-Th nanowires in PAA. The results show that the emission properties of polymers with nanostructures can be tuned by controlling their size.
基金Project supported by the National Basic Research Program of China(Grant Nos.2013CB933304 and 2012CB932701)the National Natural Science Foundation of China(Grant Nos.61274125 and 61435012)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB01010200)
文摘In this study, two-section mode-locked semiconductor lasers with different numbers of quantum wells and different types of waveguide structures are made. Their ultrashort pulse features are presented. The spectral dynamical behaviors in these lasers are studied in detail. In the simulation part, a two-band compressive-strained quantum well（QW） model is used to study thermally induced band-edge detuning in the amplifier and saturable absorber（SA）. A sudden blue shift in laser spectrum is expected by calculating the peak of the net gain. In the experiment part, the sudden blue shift in the emission spectrum is observed in triple QW samples under certain operating conditions but remains absent in single QW samples.Experimental results reveal that blue shift phenomenon is connected with the difference between currents in two sections.Additionally, a threshold current ratio for blue-shift is also demonstrated.
文摘The optical properties of Silicon-doped InGaN and GaN grown on sapphire by MOCVD have been investigated by photoluminescence (PL) method. At room temperature, the band-gap peak of InGaN is 437.0 nm and its full width of half-maximum (FWHM) is about 14.3 nm. The band-gap peak and FWHM for GaN are 364.4 nm and 9.5 nm, respectively. By changing the temperature from 20 K to 293 K, it is found that the PL intensity of samples decreases but the FWHM broadens with the increasing of the temperature. GaN sample shows red-shift, InGaN sample shows red-blue-red-shift. The temperature dependence of peak energy shift is studied and explained.
文摘The hydrogen bonding interaction of formic acid-, formaldehyde-, formylfluoride-nitrosyl hydride complexes was investigated by the density functional theory （DFT） and ab inito method in conjunction with 6-311＋＋G（2d,2p） basis set. The geometries, vibrational frequencies and interaction energies of the complexes were calculated by both standard and CP-corrected methods respectively. Moreover, G3B3 method was employed to estimate the interaction energies. There are C--H…O, N--H…O, N--H…F blue-shifted H-bonds and red-shifted O----H…O H-bond in the complexes. Electron density redistribution and rehybridization contribute to the N--H and C--H blue shifts. All geometric reorganizations contribute to the N--H blue shifts and partial geometric reorganizations contribute to the C--H blue shifts. The geometric reorganizations of the complex C except ZH（5）-O（4）-C（1） contribute to the O----H red shift. For the N--H blue shifts, the effect of r（N--O） variation on the N--H blue shifts is larger than that of ZH-N-O variation. Rehybridization plays a dominant role in the degree of N--H blue shifts, whereas the electron density redistribution contributes more to the degree of C--H blue shifts than the other effects do.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 60076002) and the Natural Science Foundation of Jiangsu Province (Grant No. BK99004).
文摘The porous alumina have been prepared by anodization and an organic molecule 8-hydroxyquinoline aluminum (Alq3) has been impregnated in the pores. The morphology measured through atomic force microscopy shows that the size of the pores is about 10 nm. A blue-shift photoluminescence of Alq3 in nanometer-sized hole is close to that of the monomers. The measured spectral characteristics demonstrate the limitation of the porous alumina to the emission of Alq3.
基金supported by the National Natural Science Foundation of China (NSFC) (No.12164030)Young Science and Technology Talents of Inner Mongolia (No.NJYT22101)Central Government Guides Local Science and Technology Development Fund (No.2023ZY0005)
文摘Mamyshev oscillators (MOs) exhibit the potential for generating high average power and ultrashort pulses. Herein,we construct an MO using flexible double-cladding ytterbium-fiber with a fusion-spliced-combiner pumped scheme.Consistent with the most reported research results, the offset filter separation significantly affects the pulse characteristics(spectrum, pulse duration, etc.). Notably, in comparison with red-shifting, blue-shifting the peak spectral emission of the grating filter relative to a constant central wavelength of the bandpass filter substantially enhances the laser output characteristics. This phenomenon, which has not been previously reported, results in an average power up to 2.23 W and a pulse duration as short as 49 fs. To our knowledge, this is the highest average power achieved in sub-50 fs pulse duration in the nonlinear polarization rotation-assisted mode-locked MO laser architecture. The presented technique offers unique scientific proof for developing ultrafast laser sources with higher average power and shorter pulse duration.
