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1.
Artigo em Inglês | MEDLINE | ID: mdl-30878847

RESUMO

The feasibility of the hybrid nanocomposites of the graphene quantum dot (GQD) and carbazole-carbazole dyes as the efficient sensitizer of dye-sensitized solar cells (DSSC) is investigated. By using the first principles density functional theory (DFT), we fully optimize the geometrical structures of GQD, the carbazole-carbazole dyes, and their hybrid nanocomposites. The harmonic frequency analysis is used to confirm the energy stability of the optimized structures. The optical absorptions of the structures are calculated with the time-dependent DFT (TDDFT). Using the I-/I3- electrolyte and the conduction band minimum of TiO2 electrode as a sample, we examine the feasibility of the nanocomposites as the sensitizer of DSSC with the charge spatial separation and the molecular orbital energy levels of the nanocomposites. The results demonstrate all the considered nanocomposites have suitable energy levels of the frontier orbitals and significantly charge spatial separation. TDDFT results show the oscillator strengths of all nanocomposites demonstrate the obvious enhancement in the visible light region. Moreover, the appropriate open-circuit voltage value, the larger light-harvesting efficiency, and larger driving force are also identified for these nanocomposites. Therefore, the nanocomposites could be the more promising candidates of sensitizer for DSSC in comparison with the separate carbazole-carbazole dyes.

2.
Artigo em Inglês | MEDLINE | ID: mdl-30594854

RESUMO

To evaluate the feasibility of the laser cooling of CuH molecule, we investigate the electronic properties, the vibrational and rotational characteristics of the molecule based on the multi-reference configuration interaction method with all-electron basis sets. The potential energy curves (PECs) of X1Σ+, A1Σ+, B1Σ+, a3Σ+, b3Σ+, e3Σ+, C1П, D1П, c3П and d3П states and the transition dipole moments between these states are calculated. The Schrödinger equation of nuclear movement is solved for each electronic state to obtain the rotational and vibration energy levels. The spectroscopic parameters are calculated based on the fitted analytical function from the PECs. The present results are in good agreement with the theoretical and experimental values available in the literature. The optical scheme of the laser cooling for CuH molecule is constructed with A1Σ+ ↔ X1Σ+ as the close-loop transition. Three lasers are necessary in each direction to maintain enough scattering photons because of the limited Franck-Condon factor of 0.78. The wavelengths of the pumping lasers are determined. The recoil temperature is 1.72 µk, which is the expected temperature to be reached through the method of the cooling below the doppler limit.

3.
Artigo em Inglês | MEDLINE | ID: mdl-30513480

RESUMO

Based on the first principles calculations, the feasibility of the photocatalytic hydrogen production from water splitting driven by N-doped ß-Ga2O3 in the visible light is investigated. The formation energy and dynamics properties are used to examine the stability of the doped structures. The absolute positions of the band energy edges are obtained and compared to the redox potentials of the hydrogen production reaction. Moreover, we calculate the carrier lifetime and mobility for both electron and hole of all the considered structures. The optical absorption is also calculated for each structure. The results show that the 5.00 at.% N-doped ß-Ga2O3 has the satisfactory band energy edges, obvious difference of mobilities between electron and hole, and significant enhancement of absorption in visible light range, indicating it is a promising photocatalytic material to catalyze hydrogen production from water splitting under the irradiation of the visible light.

4.
J Phys Chem Lett ; 9(11): 3087-3092, 2018 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-29790352

RESUMO

We developed a high-performance photodetector based on (CH3NH3)3Sb2I9 (MA3Sb2I9) microsingle crystals (MSCs). The MA3Sb2I9 single crystals exhibit a low-trap state density of ∼1010 cm-3 and a long carrier diffusion length reaching 3.0 µm, suggesting its great potential for optoelectronic applications. However, the centimeter single crystal (CSC)-based photodetector exhibits low responsivity (10-6 A/W under 1 sun illumination) due to low charge-carrier collection efficiency. By constructing the MSC photodetector with efficient charge-carrier collection, the responsivity can be improved by three orders of magnitude (under 1 sun illumination) and reach 40 A/W with monochromatic light (460 nm). Furthermore, the MSC photodetectors exhibit fast response speed of <1 ms, resulting in a high gain of 108 and a gain-bandwidth product of 105 Hz. These numbers are comparable to the lead-perovskite single-crystal-based photodetectors.

5.
Spectrochim Acta A Mol Biomol Spectrosc ; 195: 176-183, 2018 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-29414576

RESUMO

The feasibility of nanocomposites of cir-coronene graphene quantum dot (GQD) with phthalocyanine, tetrabenzoporphyrin, tetrabenzotriazaporphyrins, cis-tetrabenzodiazaporphyrins, tetrabenzomonoazaporphyrins and their Cu-metallated macrocycles as a sensitizer of dye-sensitized solar cells (DSSC) are investigated. Based on the first principles density functional theory (DFT), the geometrical structures of the separate GQD and 10 macrocycles, and their hybridized nanocomposites are fully optimized. The energy stabilities of the obtained structures are confirmed by harmonic frequency analysis. The optical absorptions of the optimized structures are calculated with time-dependent DFT. The feasibility of the nanocomposites as the sensitizer of DSSC is examined by the charge spatial separation, the electron transfer, the molecular orbital energy levels of the nanocomposites and the electrolyte, and the conduction band minimum of TiO2 electrode. The results demonstrate that all the nanocomposites have enhanced absorptions in the visible light range, and their molecular orbital energies satisfy the requirement of sensitizers. However, only two of the ten considered nanocomposites demonstrate significantly charge spatial separation. The GQD-Cu-TBP is identified as the most favorable candidate sensitizer of DSSC by the most enhanced in optical absorption, obvious charge spatial separation, suitable LUMO energy levels and driving force for electron transfer, and low recombination rate of electron and hole.

6.
Artigo em Inglês | MEDLINE | ID: mdl-29223057

RESUMO

The potential energy curves and transition dipole moments of 12Σ+ and 12Π states of GaH+ and InH+ cations are performed by employing ab initio calculations. Based on the potential energy curves, the rotational and vibrational energy levels of the two states are obtained by solving the Schrödinger equation of nuclear movement. The spectroscopic parameters are deduced with the obtained rovibrational energy levels. The spin-orbit coupling effect of the 2Π states for both the GaH+ and InH+ cations are also calculated. The feasibility of laser cooling of GaH+ and InH+ cations are examined by using the results of the electronic and spectroscopic properties. The highly diagonal Franck-Condon factors and appropriate radiative lifetimes are determined by using the potential energy curves and transition dipole moments for the 2Π1/2, 3/2↔12Σ+ transitions. The results indicate that the 2Π1/2, 3/2↔12Σ+ transitions of both GaH+ and InH+ cations are appropriate for the close cycle transition of laser cooling. The optical scheme of the laser cooling is constructed for the GaH+ and InH+ cations.

7.
Spectrochim Acta A Mol Biomol Spectrosc ; 185: 365-370, 2017 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-28601040

RESUMO

The potential energy curves and transition dipole moments of 12Σ+, 22Σ+, 12Π and 22Π states of NH+ cation and NH- anion are calculated by using multi-reference configuration interaction method and large all-electron basis sets. Based on the obtained potential energy curves, the rotational and vibrational energy levels of the states are obtained by solving the Schrödinger equation of nuclear movement. The calculated spectroscopic parameters for NH+ cation and NH- anion are in good agreement with available theoretical and experimental results. The spin orbit coupling effect of the 2Π states for both NH+ cation and NH- anion are calculated. The feasibility of laser cooling of the two molecules is examined by using the results of the molecular structure and spectroscopy. The highly diagonal Franck-Condon factors for the 12Π (v″=0)↔12Σ+ (v'=0) transition of NH+ and NH- are 0.821 and 0.999, while the radiative lifetimes of the 12Σ+ (v'=0) state for the two molecules are 384ns and 52.4ns, respectively. The results indicate that NH+ cation and NH- anion are good candidate molecules for laser cooling. The cooling scheme via Sisyphus process for the NH+ cation and NH- anion are proposed in the paper. The laser wavelengths for the close cycles of the absorption and radiation are also determined. Unfortunately, the potential energy curve of the ground state of the neutral NH molecule shows that the auto-detachment of NH- anion is possible, implying the optical scheme of laser cooling for NH- anion is not easy to achieve in the experiment although it has larger Franck-Condon factor.

8.
Spectrochim Acta A Mol Biomol Spectrosc ; 182: 130-135, 2017 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-28431311

RESUMO

The potential energy curves and transition dipole moments for the 12Σ+, 22Σ+, 12Π and 22Π electronic states of the two molecules are calculated using multi-reference configuration interaction and the large basis sets aug-cc-pwCV5Z. Based on the obtained potential energy curves, the rotational and vibrational energy levels of the states are obtained by solving the Schrödinger equation of nuclear motion, and the spectroscopic parameters are then obtained by fitting the energy levels to Dunham series expansions. The spin-orbit coupling effect of the 2Π states for both the BH+ cation and BH- anion are calculated. Highly diagonally distributed Franck-Condon factors are determined for the 12Σ+ (v″=0)↔12Π (v'=0) transition, ƒ00 (BH+)=0.943, while the Franck-Condon factors for the 12Π (v″=0)↔12Σ+ (v'=0) transition is ƒ00 (BH-)=0.942. Moreover, the radiative lifetime of 38.2ns for the excited 12Π state of the BH+ and 91.8ns for the 12Σ+ state of the BH- are obtained, which are short enough for rapid laser cooling. A three-step optical scheme of the laser cooling is constructed for either the BH+ cation or the BH- anion.

9.
J Chem Phys ; 146(12): 124312, 2017 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-28388148

RESUMO

The photoisomerization mechanisms of N-salicilydenemethylfurylamine upon excitation to the first singlet state are investigated by means of surface-hopping dynamics simulations based on the Zhu-Nakamura theory. Due to different orientations of the methyl-furyl part with respect to the salicylaldimine part and different orientations of hydroxy group with respect to the benzene ring, various stable structures are obtained in the optimization. The enol isomer, S0-ENOL-5a, is the most stable conformer. An ultrafast excited-state intramolecular proton transfer is observed after photoexcitation of the most stable enol conformer and then the molecule reaches the excited-state minimum. After the internal conversion around a conical intersection, the system relaxes to either the cis-keto or trans-keto region in the ground state. The potential energy profiles of the ground and the first excited singlet state are also calculated. According to full-dimensional nonadiabaticdynamics simulations and potential energy profiles, the trans-keto and cis-keto photoproducts can be responsible for the photochromic effect of N-salicilydenemethylfurylamine.

10.
Phys Chem Chem Phys ; 18(29): 19838-46, 2016 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-27388722

RESUMO

The spin-forbidden cooling of the LiRb molecule is investigated based on ab initio quantum chemistry calculations. The multireference configuration interaction method is used to generate the potential energy curves (PECs) of the ground state X(1)Σ(+) and the low-lying excited states a(3)Σ(+), B(1)Π, and b(3)Π. The spin-orbit coupling effects for the PECs and the transition dipole moments (TDMs) between the X(1)Σ(+), b(3)Π and a(3)Σ(+) states are also calculated. The analytical functions for the PECs are deduced. The rovibrational energy levels, the spectroscopic parameters and the Franck-Condon factors (FCF) are determined by solving the Schrödinger equation of nuclear movement with the obtained analytical functions. The b(3)Π0 ↔ X(1)Σ(+) and b(3)Π1 ↔ X(1)Σ(+) transitions have highly diagonal distributed FCFs and non-zero TDMs, demonstrating that the LiRb molecule could be a very promising candidate for laser cooling. Therefore, a three-cycle laser cooling scheme for the molecule has been proposed based on these two spin-forbidden transitions. Using the radiative lifetime and linewidth calculated from the obtained TDM functions, we present further analysis of the cooling of LiRb and the corresponding KRb molecule. The transition b(3)Π0 ↔ X(1)Σ(+) is found to be a practical transition to cool the LiRb molecule, and a sub-microkelvin cool temperature could be reached for the KRb molecule using a similar laser cooling scheme.

11.
Spectrochim Acta A Mol Biomol Spectrosc ; 153: 488-95, 2016 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-26397035

RESUMO

The analytic potential energy functions (APEFs) of the X(1)Σ(+), 2(1)Σ(+), a(3)Σ(+), and 2(3)Σ(+) states of the LiRb molecule are obtained using Morse long-range potential energy function with damping function and nonlinear least-squares method. These calculations were based on the potential energy curves (PECs) calculated using the multi-reference configuration interaction (MRCI) method. The reliability of the APEFs is confirmed using the curves of their first and second derivatives. By using the obtained APEFs, the rotational and vibrational energy levels of the states are determined by solving the Schrödinger equation of nuclear movement. The spectroscopic parameters, which are deduced using Dunham expansion, and the obtained rotational and vibrational levels are compared with the reported theoretical and experimental values. The correlation effect of the electrons of the inner shell remarkably improves the results compared with the experimental spectroscopic parameters. For the first time, the APEFs for the dipole moments and transition dipole moments of the states have been determined based on the curves obtained from the MRCI calculations.

12.
Zygote ; 23(3): 336-41, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24355553

RESUMO

Round spermatid injection (ROSI) into mammalian oocytes can result in the development of viable embryos and offspring. One current limitation to this technique is the identification of suitable round spermatids. In the current paper, round spermatids were selected from testicular cells with phase contrast microscopy (PCM) and fluorescence-activated cell sorting (FACS), and ROSI was performed in two strains of mice. The rates of fertilization, embryonic development and offspring achieved were the same in all strains. Significantly, round spermatids selected by PCM and FACS were effectively used to rescue the infertile Pten-null mouse. The current results indicate that FACS selection of round spermatids can not only provide high-purity and viable round spermatids for use in ROSI, but also has no harmful effects on the developmental capacity of subsequently fertilized embryos. It was concluded that round spermatids selected by FACS are useful for mouse strain rederivation and rescue of infertile males; ROSI should be considered as a powerful addition to the armamentarium of assisted reproduction techniques applicable in the mouse.


Assuntos
Citometria de Fluxo/métodos , Injeções de Esperma Intracitoplásmicas/métodos , Espermátides/citologia , Animais , Transferência Embrionária , Feminino , Masculino , Camundongos Endogâmicos ICR , Camundongos Mutantes , Camundongos Transgênicos , Microscopia de Contraste de Fase , PTEN Fosfo-Hidrolase/genética , Gravidez , Taxa de Gravidez , Espermátides/fisiologia , Testículo/citologia
13.
J Phys Chem A ; 118(39): 9148-56, 2014 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-24749701

RESUMO

The potential energy curves (PECs) and dipole moment functions of (1)Π, (3)Π, (1)Σ(+), and (3)Σ(+) states of BAlk (Alk = Li, Na, K) are calculated using multireference configuration interaction method and large all-electron basis sets. The effects of inner-shell correlation electron for BAlk are considered. The ro-vibrational energy levels are obtained by solving the Schrödinger equation of nuclear motion based on the ab initio PECs. The spectroscopic parameters are determined from the ro-vibrational levels with Dunham expansion. The PECs are fitted into analytical potential energy functions using the Morse long-range potential function. The dipole moment functions for the states of BAlk are presented. The transition dipole moments for (1)Σ(+) → (1)Π and (3)Σ(+) → (3)Π states of BAlk are obtained. The interactions between the outermost electron of Alk and B 2p electrons for (1)Π, (3)Π, (1)Σ(+), and (3)Σ(+) states are also analyzed, respectively.


Assuntos
Lítio/química , Potássio/química , Sódio/química , Algoritmos , Compostos de Boro/química , Elétrons , Análise Espectral , Vibração
14.
PLoS One ; 8(10): e78437, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24167624

RESUMO

The birthrate following round spermatid injection (ROSI) remains low in current and evidence suggests that factors in the germinal vesicle (GV) cytoplasm and certain substances in the GV such as the nucleolus might be responsible for genomic reprogramming and embryonic development. However, little is known whether the reprogramming factors in GV oocyte cytoplasm and/or nucleolus in GV are beneficial to the reprogramming of round spermatids and development of ROSI embryos. Here, round spermatids were treated with GV cytolysates and injected this round spermatid alone or co-injected with GV oocyte nucleolus into mature metaphase II oocytes. Subsequent embryonic development was assessed morphologically and by Oct4 expression in blastocysts. There was no significant difference between experimental groups at the zygote to four-cell development stages. Blastocysts derived from oocytes which were injected with cytolysate treated-round spermatid alone or co-injected with nucleoli injection yielded 63.6% and 70.3% high quality embryos, respectively; comparable to blastocysts derived by intracytoplasmic sperm injection (ICSI), but higher than these oocytes which were co-injected with lysis buffer-treated round spermatids and nucleoli or injected with the lysis buffer-treated round spermatids alone. Furthermore, the proportion of live offspring resulting from oocytes which were co-injected with cytolysate treated-round spermatids and nucleoli or injected with cytolysate treated-round spermatids alone was higher than those were injected with lysis buffer treated-round spermaids, but comparable with the ICSI group. Our results demonstrate that factors from the GV cytoplasm improve round spermatid reprogramming, and while injection of the extra nucleolus does not obviously improve reprogramming its potential contribution, although which cannot be definitively excluded. Thus, some reprogramming factors are evidently present in GV oocyte cytoplasm and could significantly facilitate ROSI technology, while the nucleolus in GV seems also having a potential to improve reprogramming of round spermatids.


Assuntos
Nucléolo Celular/metabolismo , Nucléolo Celular/transplante , Citoplasma/metabolismo , Oócitos , Espermátides , Animais , Blastocisto/citologia , Blastocisto/metabolismo , Feminino , Masculino , Camundongos , Fator 3 de Transcrição de Octâmero/biossíntese , Oócitos/citologia , Oócitos/metabolismo , Injeções de Esperma Intracitoplásmicas , Espermátides/citologia , Espermátides/metabolismo
15.
J Chem Phys ; 139(7): 074305, 2013 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-23968090

RESUMO

The potential energy curves (PECs) of 1(2)Σ(+), 2(2)Σ(+), 1(2)Π, and 2(2)Π states of KBe are calculated using multireference configuration interaction method and large all-electron basis sets. Four sets of frozen core orbitals (FCOs) are considered to examine the effect of inner-shell correlation electrons on the molecular properties. The ro-vibrational energy levels are obtained by solving the Schrödinger equation of nuclear motion based on the ab initio PECs. The spectroscopic parameters are determined from the ro-vibrational levels with Dunham expansion. The PECs are fitted into analytical potential energy functions using the Morse long-range potential function. The dipole moment functions of the states for KBe calculated with different FCOs are presented. The transition dipole moments for KBe between 1(2)Σ(+) and 2(2)Σ(+) states, 1(2)Π and 1(2)Σ(+) states, and 2(2)Π and 1(2)Σ(+) states are also obtained.

16.
J Phys Chem A ; 117(1): 3-8, 2013 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-23210502

RESUMO

Using the multireference configuration interaction method with the Davidson correction and a large orbital basis set (aug-cc-pV5Z), we obtain an energy grid that includes 17,500 points for the construction of a new analytical potential energy surface (APES) for the N((2)D) + H(2)(X(1)Σ(g)(+)) → NH(X(3)Σ(-)) + H((2)S) reaction. The APES, which contains 145 parameters and is represented with a many-body expansion and a new switch function, is fitted from the ab initio energies using an adaptive nonlinear least-squares algorithm. The geometric characteristics of the reported APES in the literature and those of our APES are also compared. On the basis of the APES that we obtained, reaction cross sections are computed by means of quasi-classical trajectory calculations and compared with the experimental and theoretical values available in the literature.

17.
Artigo em Inglês | MEDLINE | ID: mdl-23041922

RESUMO

The potential energy curves (PECs) of the ground state X(1)Σ(+) and two low-lying excited states 1(3)Σ(+) and 1(3)П of KRb molecule have been calculated using the multireference configuration interaction method and the effective core potential basis set. The PECs are fitted into analytical potential energy functions (APEFs) using the Morse long-range potential. The spectroscopic parameters for the states are determined using the analytical derivatives of APEFs. The vibrational energy levels have been calculated by solving the radial Schrödinger equation of nuclear motion based on the APEFs, and compared with the theoretical and experimental works available at present.


Assuntos
Potássio/química , Rubídio/química , Elétrons , Conformação Molecular , Teoria Quântica , Análise Espectral
18.
J Phys Chem B ; 116(7): 2040-7, 2012 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-22239409

RESUMO

Information on the interfacial interaction is vital in understanding the crystallization of short polymer chains around oriented nuclei. However, this interaction is difficult to observe at the atomic level. Molecular dynamics simulations are performed to investigate the structural formation of polymer chains induced by the highly oriented slab or the stretched bundle of polymer chains. The results show that the surface-induced crystallization of polymer chains is greatly influenced by the foreign surface on the crystal structure and the morphology of the polymers, hence providing molecular-level support for previous experimental observations [Lotz et al. Macromolecules 1993, 26, 5915 and Yan et al. Macromolecules 2009, 42, 9321]. The order parameter S and the configurations show that the ability of the polypropylene (PP) slab to induce the polyethylene (PE) melt crystallization is weaker than that of the PE slab and that the short PE chains display multiple orientations on the PP slab. In addition, the crystallization rate was found to be dependent on the lattice matching between the free chains and the substrates on the contact lattice planes.

19.
Phys Chem Chem Phys ; 13(34): 15476-82, 2011 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-21808771

RESUMO

The crystallization of alkane melts on carbon nanotubes (CNT) and the surface of graphene nanosheets (GNS) is investigated using molecular dynamics (MD) simulations. The crystallization process of the alkane melts is analyzed in terms of the bond-orientational order parameter, atomic radial distribution for the CNT/alkane, atomic longitudinal distribution for the GNS/alkane, and diffusion properties. The dimensional effects of the different carbon-based nanostructures on the crystallization of alkane melts are shown. It is found that one-dimensional CNT has a stronger ability to induce the crystallization of the polymer than that of two-dimensional GNS, which provides a support at molecular level for the experimental observation [Li et al., J. Am. Chem. Soc., 2006, 128, 1692 and Xu et al., Macromolecules, 2010, 43, 5000]. From the MD simulations, we also find that the crystallization of alkane molecules has been completed with the highly cooperative processes of adsorption and orientation.

20.
J Phys Chem A ; 115(9): 1486-92, 2011 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-21322539

RESUMO

Using the multireference configuration interaction method with a Davidson correction and a large orbital basis set (aug-cc-pVQZ), we obtain an energy grid that includes 32 038 points for the construction of a new analytical potential energy surface (APES) for the Ne + H(2)(+) → NeH(+) + H reaction. The APES is represented as a many-body expansion containing 142 parameters, which are fitted from 31 000 ab initio energies using an adaptive nonlinear least-squares algorithm. The geometric characteristics of the reported APES and the one presented here are also compared. On the basis of the APES we obtained, reaction cross sections are computed by means of quasi-classical trajectory (QCT) calculations and compared with the experimental and theoretical data in the literature.

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