Search

Charge state is a key factor for the ion stopping and energy deposition. It is helpful to understand the physics mechanics for interaction between ion and target by studying the charge state. In this paper, nitrogen molecular ion charge evolution in Ag target is studied. It is shown that the charge state of the trailing ion is oscillating, while the leading ion doesn’t show the similar behavior due to the wake effects aroused by the electronic exciting of the target electron.

In this paper, three modified π-conjugated bridges, were selected to study the relationship between substituted alkyl chains and two photon absorption ability as well as intramolecular charge transfer property. The modification is on the N-atom position of Diketo-Pyrrole-Pyrrole bridges. Some nonlinear optical measurements as well as several spectra methods, were used. DPP-J0, DPP-J1 and DPP-J2 exhibit cross-section of 5.6 GM, 8.1 GM, and 6.4 GM. The results exhibit obvious relation on the length and symmetry of N-atom position substituted alkyl chains. A pump-probe measurement was operated at 800 nm. Ultrafast dynamics results exhibit slight difference on the intramolecular charge transfer of these conjugated bridge derivatives. The quantum chemical calculations results are well accorded with the nonlinear optical properties. The results obtained may provide some useful information on molecular design and optimization of new advanced materials.

Based on the extended Huygens–Fresnel principle, the cross-spectral density function of a partially coherent anomalous hollow vortex beam (AHVB) propagating in underwater oceanic turbulence has been derived, and the influences of the beam parameters and underwater oceanic turbulence on the average intensity and coherence properties are investigated by using numerical examples. Our results show that the partially coherent AHVB with smaller coherence length and smaller M will evolve into the flat-topped faster as the propagation distance increases, and the partially coherent AHVB propagating in stronger underwater oceanic turbulence (the larger χ T and ς or the smaller e ) will lose the initial dark hollow center and evolve into the Gaussian beam more rapidly. In the influences of oceanic turbulence on the spreading of partially coherent AHVB, it is found that the parameters χ T and ς will cause the larger spreading than the parameter e at the same propagation distance. This research is useful to the practical application of the partially coherent AHVB beam in underwater oceanic turbulence.

The propagation equation of a four-petal Lorentz-Gauss (LG) beam propagating in uniaxial crystal orthogonal to the optical axis is derived, and the influences of uniaxial crystal and source beam on the spreading of a four-petal LG beam are analyzed by using the derived equations. The results show that a four-petal LG beam propagating in uniaxial crystal will evolve from four-petal distribution into an elliptical Gaussian-like beam surrounded by the smaller beamlets as the propagation distance increases due the influences of uniaxial crystal. The results also show that beam width of an elliptical Gaussian-like beam can be modulated by the source beam parameter and uniaxial crystal in the far field.

The concept of a four-petal Lorentz-Gauss beam was first introduced, which is consisted by Lorentz part and Gaussian part. Based on the Collins integral formula, the equation of a four-petal Lorentz-Gauss beam propagating in ABCD optical system was derived. The propagation properties of a four-petal Lorentz-Gauss bean in free space was illustrated and analyzed using numerical examples. The intensity distributions of four-petal Lorentz-Gauss beam can be modulated by the beam waist of Lorentz part, and the beam will evolve into a larger Gaussian-like beam in the center around by smaller beamlets in the far field.

Based on the extended Huygens-Fresnel principle, the propagation equations of rectangular multi-Gaussian Schell-model (MGSM) beam array generated by the multi-Gaussian Schell-model source in maritime atmospheric turbulence are derived. The evolutions and effective beam widths of MGSM beam array propagating in maritime atmospheric turbulence are analyzed by using numerical examples. The obtained results are beneficial to the practical application of MGSM beam array in maritime atmosphere.

In this paper, rectangular multi-Gaussian Schell-model (MGSM) array beams, which consists N&times, D beams in rectangular symmetry, are first introduced. The analytical expressions of MGSM array beams propagating through free space and non-Kolmogorov turbulence are derived. The propagation properties, such as normalized average intensity and effective beam sizes of MGSM array beams are investigated and analyzed. It is found that the propagation properties of MGSM array beams depend on the parameters of the MGSM source and turbulence. It can also be seen that the beam size of Gaussian beams translated by MGSM array beams will become larger as the total number of terms, M, increases or coherence length, &sigma, decreases, and the beam in stronger non-Kolmogorov turbulence (larger &alpha, and l 0 , or smaller L 0 ) will also have a larger beam size.

In this work, the laser effects on the stopping for boron ion in plasmas are studied by molecular dynamics (MD) simulation. The expressions of the stopping power is derived based on the potential. The effects of different laser intensity, laser frequency, laser angle, plasma density and electron temperature on the stopping power of B+ ion are discussed. The results tell that the stopping power of B+ ion will decrease significantly with the increase of laser intensity, and the laser intensity has a strong modulation effect on the stopping power. On the other hand, when the included angle between the laser and the moving direction of boron ion is in the range of 0 to π / 2, the stopping power decreases gradually with the increase of the projectile angle. On the other hand, the influence of plasma parameters on the stopping power of boron ions is also very obvious. When other parameters are given, the increase of plasma temperature or the decrease of plasma density can decrease the value of stopping power.

Femtosecond open-aperture Z-scan and two-photon excited fluorescence method, were performed to study the two-photon absorption cross-section of several tri-branched derivatives. The two-photon absorption cross-section values measured by the two different methods were compared. Our results indicate that, the absolute values of the two-photon absorption cross-section measured by different technique are obviously different. The absorption cross-sections measured by two-photon excited fluorescence method exhibited 2.1–2.3 times larger than that measured by open-aperture Z-scan method. And the difference is most likely caused by the system error of different measurements. Our results may provide scientific responsible reference as well as some useful information for the comparison of the two-photon absorption cross-section values measured by different methods.

The propagation properties of a partially coherent Lorentz-Gauss vortex beam propagating in a uniaxial crystal orthogonal to the optical axis were studied. The analytical expressions of the partially coherent Lorentz-Gauss vortex beam propagating in a uniaxial crystal were derived. Based on the derived formulae, the average intensity properties and evolution properties of the coherent vortex of the partially coherent Lorentz-Gauss vortex beam propagating in a uniaxial crystal were illustrated using numerical examples. The influences of the uniaxial crystal and the parameters of the beam at the source plane of z = 0 on the average intensity and evolution properties of the coherent vortex for the partially coherent Lorentz-Gauss vortex beam are analyzed in detail.

In the analysis of the nonparaxial propagation and far field propagation, the analytical propagation equations of a partially coherent four-petal Gaussian vortex beam have been derived based on the Rayleigh-Sommerfeld diffraction. The properties of nonparaxial propagation properties of a partially coherent four-petal Gaussian vortex beam have been obtained and analyzed using the numerical examples. And the influences of beam parameters on the average intensity of nonparaxial and far field propagation properties of partially coherent four-petal Gaussian vortex beam have been analyzed.

The concept of a partially coherent anomalous hollow vortex beam generated by a Schell-model source was introduced in this paper. Next, the analytical expressions of a partially coherent anomalous ...

We summarize our theoretical studies for stopping power of energetic heavy ion, diatomic molecular ions and small clusters penetrating through plasmas. As a relevant research field for the heavy ion inertial confinement fusion (HICF), we lay the emphasis on the dynamic polarization and correlation effects of the constituent ion within the molecular ion and cluster for stopping power in order to disclose the role of the vicinage effect on the Coulomb explosion and energy deposition of molecules and clusters in plasma. On the other hand, as a promising scheme for ICF, both a strong laser field and an intense ion beam are used to irradiate a plasma target. So the influence of a strong laser field on stopping power is significant. We discussed a large range of laser and plasma parameters on the coulomb explosion and stopping power for correlated-ion cluster and C60 cluster. Furthermore, in order to indicate the effects of different cluster types and sizes on the stopping power, a comparison is made for hydrogen and carbon clusters. In addition, the deflection of molecular axis for diatomic molecules during the Coulomb explosion is also given for the cases both in the presence of a laser field and laser free. Finally, a future experimental scheme is put forward to measure molecular ion stopping power in plasmas in Xi'an Jiaotong University of China. Keywords: Molecules, Stopping power, Coulomb explosion, Vicinage effect, Laser, PACS Codes: 34.50.Bw, 52.40.Mj, 61.85.+p, 34.50.Dy

Based on the Huygens-Fresnel integral and the relationship of Lorentz distribution and Hermite-Gauss function, the average intensity and coherence properties of a partially coherent Lorentz-Gauss beam propagating through oceanic turbulence have been investigated by using numerical examples. The influences of beam parameters and oceanic turbulence on the propagation properties are also discussed in details. It is shown that the partially coherent Lorentz-Gauss beam with smaller coherence length will spread faster in oceanic turbulence, and the stronger oceanic turbulence will accelerate the spreading of partially coherent Lorentz-Gauss beam in oceanic turbulence.

Currently, primary treatment and secondary biological treatment are the main steps for the treatment of wastewater generated from pulp and paper processes. However, in many cases, in particular, in China, due to a very low COD regulation for discharge, the secondarily treated wastewater would have to be further treated. In this short communication, we present a process concept of immobilizing white rot fungi to corn cob for tertiary treatment of secondarily treated wastewater. As an agricultural residue, carbohydrate-rich corn cob can serve as the support for fungi, allowing for continuous wastewater treatment operations. The role of corn cob as a carbon source can facilitate fungal incubation. Enrichment of pollutants by corn cob could also be possible, which is definitely favorable for enhancing fungi-pollutants interactions. This concept may potentially be combined with existing wastewater treatment technologies to meet ever-demanding environmental target for discharging effluent from manufacturing processes, including pulp and paper mills.

Breast cancer (BC) is considered as one the most prevalent cancers worldwide. Due to its high resistance to chemotherapy and high probability of metastasis, BC is one of the leading causes of cancer-related deaths. The controlled release of chemotherapy drugs to the precise site of the tumor tissue will increase the therapeutic efficacy and decrease side effects of systemic administration. Among various drug delivery systems, natural polymers-based drug carriers have gained significant attention for cancer therapy. Chitosan, a natural polymer obtained by de-acetylation of chitin, holds huge potential for drug delivery applications because chitosan is non-toxic, non-immunogenic, biocompatible, chemically modifiable, and can be processed to form various formulations. In the current review, we will discuss the prospects and challenges of chitosan-based drug delivery systems in treating BC.

Based on the extended Huygens-Fresnel principle, the cross-spectral density of a Hermite-cos-Gaussian correlated Schell-model (HcGCSM) beam propagating in non-Kolmogorov turbulence is derived in theory, and the intensity distribution and coherence properties of a HcGCSM beam propagation in atmospheric turbulence and free space are studied and compared by using numerical simulations. It is found that multiple beam spots of a HcGCSM beam propagation in atmospheric turbulence will combine with each other at the long distance, and the combination properties of multiple beam spots are related with initial beam parameters and strength of atmospheric turbulence. It is also found that spectral degree of coherence of a HcGCSM beam propagation in atmospheric turbulence will decrease faster than the beam propagation in free space as | r 2 − r 1 | increases

The analytical equation of a rectangular Laguerre-Gaussian correlated Schell-model (LGCSM) beam in uniaxial crystal orthogonal to the optical axis is derived. The intensity and coherence properties of a rectangular LGCSM beam in uniaxial crystal are investigated by numerical simulations. It is shown that the symmetry of intensity and coherence distribution can be modulated by the n e / n o . When n e / n o > 1 of uniaxial crystal, the multiple beams generating by a rectangular LGCSM beam will spread faster along x-direction than y-direction at the longer distance. The physical explanations of evolutions are analyzed in detail.

The effect of modifying a 1,3,5-triazine-based multi-branched compound (T03-a) with perfluoroalkyl chains (T03-d) on the fluorescence and ultrafast dynamics was investigated by two-photon fluorescence and femtosecond transient absorption experiments. After modification, a significantly increased fluorescence quantum yield was observed. The fluorescence quantum yield of the perfluoroalkyl chain modified compound T03-d (0.86) was approximately 3.2 times greater than that of T03-a (0.27). The ultrafast dynamics experiments revealed the effect of the perfluoroalkyl chain modification on the intramolecular charge transfer (ICT) property. The ultrafast dynamics results agree with the changes in the fluorescent property. Our results indicate that the modification of compounds with perfluoroalkyl chains based on the 1,3,5-triazine tri-branched compound would be a very useful strategy for enhancement of the fluorescence, and the 1,3,5-triazine based multi-branched derivatives have the potential to be employed as molecular probes for biological fluorescence imaging.

Based on the generalized Rayleigh-Sommerfeld diffraction integral, the equations of nonparaxial propagation, far field propagation and paraxial propagation of a partially coherent four-petal Gaussian beam in free space are obtained. The results show that the far field propagation and paraxial propagation can be regarded as special cases of nonparaxial propagation. The normalized intensity and degree of coherence of a nonparaxial partially coherent four-petal Gaussian beam are illustrated and analyzed using numerical example.

Z-scan and time-resolved photoluminescence experiments were performed to study the optical limiting properties and the excited state dynamics of a series compounds based on 1,3,5-triazine. The optical limiting properties were greatly enhanced when multi-branched structural configurations were built. The more branches the better optical limiting properties. The fluorescence quantum yields of multi-branched compounds were decreased with the number of the branches. Obvious different excited states responses were determined by time-resolved photoluminescence. The fluorescence lifetimes were determined to be ∼2.9 ns, ∼2.3 ns, and ∼0.5 ns, for compounds with linear, tri-branched, and six-branched structural configurations, respectively. The obtained ultrafast dynamics properties are well accorded with the fluorescence quantum yield results.

Based on the extended Huygens–Fresnel integral formula, the analytical expressions for partially coherent four-petal Gaussian beam propagating in oceanic turbulence are derived, and the influences of coherence length, beam order N and the parameters of oceanic turbulence (the rate of dissipation of turbulent kinetic energy per unit mass of fluid, the rate of dissipation of mean square temperature and the relative strength of temperature and salinity fluctuations) on average intensity properties are investigated using numerical examples in detail. The results show that the beam with the higher beam order N or coherence length will lose its initial four-petal profiles slower. It is also indicated that the beam will evolve into a Gauss-like beam more rapidly with increasing oceanic turbulence strength. The results have the potential application in underwater laser communication using a partially coherent four-petal Gaussian beam.

Starting from the vectorial Rayleigh-Sommerfeld integral formulae, the analytical propagation equations of vectorial flat-topped vortex hollow beam in free space are derived. The far-field and paraxial approximation can be treated as special cases of general results. According to the obtained analytical expressions, the nonparaxial propagation, far field propagation and paraxial propagation properties of flat-topped vortex hollow beam are illustrated and analyzed by using numerical examples.

Based on the extended Huygens-Fresnel diffraction integral formula, the average intensity of partially coherent flat-topped vortex hollow beam propagating through the paraxial ABCD optical system in atmosphere turbulence are investigated by using the numerical examples. The influences of optical system parameters, coherence length, parameters of turbulent atmosphere, beam order N and topological charge M of laser beam on the average intensity of partially coherent flat-topped vortex hollow beam are analyzed. Results show that the beam will evolve into Gauss-like beam in the far field with the propagation distance increasing, and the beam will evolve into Gauss-like beam more rapidly with the increasing of the structure constant of turbulent atmosphere or the decreasing of coherence length. The results of this work have the potential applications in free space optical communication.

The analytical expressions for a partially coherent flat-topped vortex hollow beam propagating in uniaxial crystals orthogonal to the optical axis are derived, and the intensity and coherent vortex properties of partially coherent flat-topped vortex hollow beam propagation in uniaxial crystals orthogonal to the optical axis are analyzed by numerical examples. The influence of beam order parameter N, topological charge M, the coherence length and the ratio of refractive indices ne/no of uniaxial crystals on the normalized intensity distribution and coherent vortex of a partially coherent flat-topped vortex hollow beam propagating in uniaxial crystals are discussed in detail.

A model of a radial phase-locked partially coherent elegant Laguerre–Gaussian (PCELG) beam array has first been introduced in theory. The analytical propagation equation for the cross-spectral density function of a radial phase-locked PCELG beam array in non-Kolmogorov medium has been derived using the extended Huygens–Fresnel principle. The average intensity and spectral degree of coherence properties of a radial phase-locked PCELG beam array propagating in non-Kolmogorov medium have been studied in details using the numerical examples. One can find that the evolution properties of a radial phase-locked PCELG beam array propagating in non-Kolmogorov medium are affected by the initial beam parameters and the non-Kolmogorov medium, and the beam array propagating in non-Kolmogorov medium will evolve into a solid beam with Gaussian-like distribution in the far field.

A new theoretical model for off-axis multi-Gaussian Schell-model hollow vortex (MGSMHV) beam generated by multi-Gaussian Schell-model (MGSM) source is introduced. The evolution properties (average intensity and beam widths) of the off-axis MGSMHV beams propagating in free space and turbulent ocean are analyzed. It is seen that the flatness of off-axis MGSMHV beam at the longer propagation distance can be controlled by choosing the source parameters total number F and coherence length σ . It is also seen that the larger effective beam sizes can be obtained by choosing the source parameters (larger total number F , or smaller coherence length σ ) or propagating in turbulent ocean with smaller rate of dissipation of kinetic energy per unit mass e , larger dissipation of mean-squared temperature x T or ratio of temperature and salinity contributions to the refractive index spectrum ζ .

To study the structure-property relationship as well as the intramolecular charge transfer properties of typical ladder-conjugated molecules, three ladder-conjugated molecules named LT2, LT3 and BPTF-2 were systematically investigated by UV–vis absorption spectra and fluorescence spectra, the open-aperture Z-scan technique, two-photon excited fluorescence and femtosecond pump-probe experiments. These ladder-conjugated molecules employ the same fluorene group as the π -bridge and the central core, with substituent changes at the terminal position. These molecules exhibit a large two-photon absorption response and two molecules emit intense two-photon fluorescence at a wavelength of 800 nm, which is a commonly used wavelength in two-photon absorption/two-photon fluorescence applications. Our results indicate that the π -bridge and the terminal group play an important role in determining the two-photon absorption response. The dynamic results obtained from degenerated pump-probe experiments revealed that the evolution times of the intramolecular charge transfer state were >1000 ps, >1000 ps, and 40 ps for LT2, LT3 and BDTF-2, respectively. The results match those of the two-photon absorption responses and the fluorescence emission properties of these ladder-conjugated molecules. Our results also indicate that ladder-conjugated molecules have potential applications in two-photon absorption/two-photon fluorescence fields.

The theoretical descriptions for a radial phase-locked multi-Gaussian Schell-model vortex (RPLMGSMV) beam array is first given. The normalized intensity and coherence distributions of a RPLMGSMV beam array propagating in free space and atmospheric turbulence are illustrated and analyzed. The results show that a RPLMGSMV beam array with larger total number N or smaller coherence length σ can evolve into a beam with better flatness when the beam array translating into the flat-topped profile at longer distance z and the flatness of the flat-topped intensity distribution can be destroyed by the atmospheric turbulence at longer distance z. The coherence distribution of a RPLMGSMV beam array in atmospheric turbulence at the longer distance will have Gaussian distribution. The research results will be useful in free space optical communication using a RPLMGSMV beam array.

Two dipolar compounds with dipicolinate as electron acceptor group named trans -dimethyl-4-[4’-( N , N -dimethylamino)-styry1]-pyridin-2,6-dicarboxylate (M-1) , trans -dimethyl-4-[4’-( N , N -diphenylamino)-styry1]-pyridin-2,6-dicarboxylate (P-1) as well as a P-1 based multi-branched octupolar compound {4-[(E)-2-(2,6-dimethoxycarbonylpyridin-4-yl) vinyl]}- N , N -bis{4-[(E)-2-(2,6-dimethoxycarbonylpyridin-4-yl)vinylphenyl]}aniline (P-3) with intense two-photon fluorescence emission properties are systematically investigated by using steady-state absorption and fluorescence spectroscopy, Z-scan, and two-photon excited fluorescence (TPF) method. The two-photon absorption cross section of octupolar compound P-3 in THF solution is determined to be 376 GM, which is approximately 12 times greater than that of dipolar counterpart P-1 (32 GM). Transient absorption spectroscopy is employed to investigate the excited state dynamics of the dipolar and octupolar compounds. The formation and relaxation lifetimes of the intra-molecular charge transfer (ICT) state are determined to be in the ranges of several picoseconds and several-hundreds of picoseconds, respectively, for all the three compounds in THF solutions. An extended π-conjugated system and increased intra-molecular cooperative effect are responsible for the observed large two-photon absorption character.

The analytical propagation expressions for the average intensity of flat-topped vortex hollow beams in atmospheric turbulence are obtained by using the extended Huygens-Fresnel diffraction integral. And the influences of atmospheric turbulence on the average intensity of flat-topped vortex hollow beams are given by numerical examples. The results show that the flat-topped vortex hollow beams propagating in atmospheric turbulence will evolve into Gaussian-like beam with the propagation distance increasing, and the beam propagating in atmospheric turbulence with larger structure constant C n 2 will lose its initial dark hollow centre more rapidly.

Nondegenerate pump-probe experiment was performed to study the effect of the environment on the excited state decay dynamics of six-branched styryl derivatives based on 1,3,5-triazine. The two compounds were dissolved in CHCl 3 solutions for research in solvent environment, and the spin-coating films were also prepared for reasearch in agglomerate state. Obvious different excited state dynamics were observed under two conditions. A fast process about several ps and a long process ∼100 ps were observed for compounds in CHCl 3 solutions. However, another ultrafast process ∼0.8 ps was observed for compounds in spin-coating film condition, indicating some other decay channels and some processes of other mechanism.

The analytical expressions of a flat-topped vortex hollow beam propagating in uniaxial crystals orthogonal to the optical axis are obtained. The evolution properties of intensity and phase for flat-topped vortex hollow beam are discussed by using the numerical examples in detail. It is found that the beam order N, topological charge M and the ratio of refractive index n e / n o of uniaxial crystals will influent the beam intensity and phase distributions.

Based on the extended Huygens-Fresnel principle, the spectral behaviors of a chirped Gaussian pulsed beam propagating in oceanic turbulence are illustrated. The influence of the parameters of oceanic turbulence (the rate of dissipation of turbulent kinetic energy per unit mass of fluid, rate of dissipation of mean-square temperature, relative strength of temperature and salinity fluctuations), relative position parameter and propagation distance on the spectra shift is analysed and given by numerical examples. The research results have the potential application in underwater wireless laser communication and remote sensing.

In this work, two-color pump-probe measurements, were performed to study the effect of the structural configuration on the excited state decay dynamics of dithienylethene photochromism systems under ring-closure state. Obvious different transient absorption dynamics were observed under parallel and perpendicular polarization configurations. The rising part of the perpendicular component probed at wavelength of 800 nm was clearly delayed compared with the parallel component, indicating some overlap between pure excited state decay dynamic and some processes of other mechanism.

Using coherence theory, the partially coherent flat-topped vortex hollow beam is introduced. The analytical equation for propagation of a partially coherent flat-topped vortex hollow beam in turbulent atmosphere is derived, using the extended Huygens-Fresnel diffraction integral formula. The influence of coherence length, beam order N, topological charge M, and structure constant of the turbulent atmosphere on the average intensity of this beam propagating in turbulent atmosphere are analyzed using numerical examples.

The cross-spectral density of a rectangular multi-Gaussian Schell-model vortex beam propagating in uniaxial crystal orthogonal to the optical axis has been derived, and the normalized intensity and effective beam widths are investigated by using numerical analysis. The results indicate that the rectangular multi-Gaussian Schell-model vortex beam propagating in uniaxial crystal will evolve from circular dark hollow beam into an elliptical flat-topped beam due to the influences of uniaxial crystal. The effective beam width W x will gradually increase as the propagation distance z increase, and the beam with larger M and N 1 = N 2 or smaller σ will have a larger effective beam width W x at the same propagation distance.