Hongxing Cai

Diode-pumped Nd:YCOB self-frequency-doubling green laser at 530 nm

We report a continuous-wave (CW) self-frequency-doubling blue laser at 468 nm by a diodepumped Nd3+:YCa4O(BO3)3 (Nd:YCOB) laser. With 14.3 W of diode pump power, a maximum output power of 211 mW in the blue spectral range at 468 nm has been achieved. The beam quality M2 values were equal to 1.16 and 1.23 in X and Y directions, respectively. The output power stability over 30 min is better than 5%. To the best of our knowledge, this is the highest power laser at 468 nm generated by self-frequency doubling of a diode pumped Nd:YCOB laser.

ZnO/Ag nanoarrays substrate for surface-enhanced Raman scattering (SERS) detection

ZnO/Ag composite nanoarrays structure have been successfully prepared through a very simple deposition method. The adherence of Ag nanoparticles to ZnO nanoarrays was realized through the deposition under normal temperature. Due to their exceptional properties, these composite nanoarrays were used as substrate in surface-enhanced Raman scattering (SERS) measurement. SERS signals of typical analytes such as Rhodamine 6G (R6G) were observed from the ZnO/Ag composite nanoarrays, which the results shows that the SERS signals can be detected when the concentration of R6G was 1×10-9 M. This work provides a new method to prepare SERS substrates for SERS detection.

Study on dispersion of photonic crystal fiber

Dispersion properties of photonic crystal fiber of fused silica with hexagonally-arranged air holes in its cladding have been investigated by using the finite-difference beam propagation method. The dependence of different PCF geometrical parameters namely the air-hole diameter and the pitch were carried out in detail. The numerical simulation results indicate that the values of dispersion monotonically reduce with the increase of air-hole diameter, and dispersion slope keep almost constant with the increase of air-hole diameter. It is also reveal that the dispersion curve is up shifted with decrease the value of pitch. We have obtained one near zero flattened dispersion with value of between -0.1~0.58ps/(km·nm) in the wavelength from 1.31 μm to 1.58 μm. Photonic crystal fiber with near zero flattened dispersion properties is of great significance to the optical fiber communication.

Theoretical Studies on the Electronic Structures and Phosphorescence Properties of Three Heteroleptic Cyclometalated Iridium(III) Complexes

The geometry structures, electronic structures, absorption, and phosphorescence properties of three heteroleptic cyclometalated iridium(III) complexes have been theoretically investigated by the density functional theory (DFT) method. The highest occupied molecular orbital (HOMO) of the three complexes has the similar distributions on two main ligands. However, the lowest unoccupied molecular orbital (LUMO) of the three complexes has different distributions on different ligand fragments. Especially for 3, the LUMO is mainly composed of the picolinate auxiliary ligand. The lowest lying absorptions were calculated to be at 409, 473, and 414 nm for 1–3, respectively. By changing the conjugation length of the main ligand from 1 to 2, one can tune the emission color from green to red. The addition of sterically bulky phenolic substituents in 3 also results in an obvious red shift of the emission wavelength. The calculated results show that the absorption and emission transition character can be changed by altering the main ligands. Calculations of ionization potential (IP) and electron affinity (EA) were used to evaluate the injection abilities of holes and electrons into these complexes. The theoretical work should provide a suitable guide to the future design and synthesis of novel phosphorescent materials for use in the organic light-emitting diodes (OLEDs).

Progress in cancer diagnosis and treatment based on gold nanorods

In this paper, the progress in cancer diagnosis and treatment were reviewed which is based on gold nanorods (Au-NRs). Synthesis and properties of Au-NRs were described, more specifically on typical methods of surface modification, surface active agent selection, as well as biological image and cancer treatment which are based on Au-NRs. Also current difficulty and future development were discussed.

Raman spectrum calculation and analysis of glyphosate

Glyphosate is an efficient, low toxicity, non-selective post-emergence herbicide. In this work, Glyphosate molecular structure was optimized by Hartree-Fock(HF) approximation method. Glyphosate molecular Raman and infrared spectra was calculated based on HF/6-31G sets and DFT/6-31G sets, then two theoretical Raman spectra were carefully compared with others experimental spectra, good agreements were obtained between the theoretical and experimental results. Glyphosate structure parameters were also given in the paper including bond lengths and bond angles etc. Vibrational modes were assigned to all bands between 850 cm-1 and 1050 cm-1 range. This work will promote the research of glyphosate molecule in pesticide residues field.

Research on the inversion of one-dimensional attitude of the space shuttle model based on scattering spectroscopy

The detection and recognition for the attitude of space target is a technical problem and research focus. In this paper the attitude inversion technique of space target was explored based scattering spectroscopy. The scattering spectra of the space shuttle model instead of space target in the laboratory were detected in 0～360° direction at 10° intervals, and the spectral database of the one-dimensional rotating space shuttle model was established. Based on spectral bidirectional reflectance distribution function (SBRDF) theoretical model, the experimental data were compared with the data in the database using residual as a reference. When the rotation angle of the space shuttle model was 8°, 68°, 293°, the angle corresponding to the minimum residual was 10°, 70°, 290°. The results indicated that the inversion of rotation angle of the space shuttle model was achieved and inversion accuracy is better than 5°. According to the redundancy of spectral data (700 effective bands), if the angle interval of spectral data was reduced, the attitude inversion of space target of higher angle accuracy can be achieved. In this paper, for the first time the one-dimensional attitude inversion of the space shuttle model was realized based on the scattering spectrum, and the correlation between scattering spectra and attitude was confirmed. This research is helpful to the application of spectroscopy in the field of the attitude inversion of space target.

Raman spectrum calculation and analysis of p-xylene

P-xylene is one of the main harmful ingredients of illegal cooking oil. This paper indicates the spatial structure of p-xylene, and the structure is optimized through density functional theory (DFT) method. Then we calculate its vibration characteristic by using Hartree-Fock (HF) and DFT separately based on 6-31G and show the spectral and infrared intensity maps. Meanwhile, we compare the Raman Spectrum with Experimental Spectrum of the two methods and get a conclusion that the results show a good consistency. Furthermore, the spatial structure parameters of p-xylene are also given in the paper including bond lengths and bond angles of each atom. Meanwhile, the vibration spectrum of p-xylene between 0 cm-1 ~ 3500cm-1 ranges is identified. These works will contribute to the research of p-xylene in the field of food detection.

Raman spectrum calculation and analysis of aflatoxin B 1

Aflatoxin Bl is one of the main harmful ingredients of illegal cooking oil which can lead to liver cancer. This paper indicates the geometry structure of aflatoxin B1, and the structure is optimized through density functional theory (DFT) method. Then we calculate its Raman Spectra and Infrared Spectra separately by using Hartree-Fock (HF) and DFT based on 6-31 G and show the spectral intensity maps. Meanwhile, we compare the Raman Spectra with Experimental Spectra of the two methods and get a conclusion that the results show a good consistency. Furthermore, the spatial structure parameters aflatoxin B1 are also given in the paper including bond lengths and bond angles of each atom. Meanwhile, the vibration spectrum of aflatoxin B1 between 500 ~ 3500cm-1 ranges is identified. These works will contribute to the research of detection of aflatoxin B1 in swill-cooked dirty oil.

Theoretical Studies on the Electronic Structures and Spectral Properties of Three Iridium(III) Complexes With Different NˆN Ligands

We report a quantum chemical study of the electronic structures and spectral properties of three iridium(III) biscarbene complexes with different heteroleptic N^N ligands. The theoretical calculation reveals that the lowest-lying singlet absorptions at 434 nm for 1 and 487 nm for 3 are attributed to the mixed transition characters of metal-to-ligand charge transfer (MLCT) and ligand-to-ligand charge transfer (LLCT). However, for 2, the lowest-lying singlet absorption at 509 nm is attributed to the MLCT. For 1–3, the phosphorescence at 739, 913, and 737 nm are mainly attributed to 3MLCT and 3LLCT characters. For 1 and 3, the emission energies are nearly the same, which is larger than that of 2. Ionization potentials (IP) and electron affinities (EA) calculations show that the assumed complex 3 has large EA value and enhanced electron injection ability as compared to complexes 1 and 2. Moreover, the reasons for different transition characters and phosphorescence quantum yield for the three complexes have been discussed in this paper. This theoretical contribution allows the factors determining the efficiency of radiative and nonradiative decay pathways in the three complexes.