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Pure red visible emission via three-photon excitation of colloidal Na3ZrF7：Er nanoparticles using a telecom-band laser

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Chinese Optics Letters 2017年第1期15卷 100-103页

作者：叶帅王广盛熊茂珍宋军屈军乐谢维信 Key Lab of Optoelectronic Devices and Systems of Ministry of Education/Guangdong Province College of Optoelectronic Engineering Shenzhen University Shenzhen 518060 China College of Information Engineering Shenzhen University Shenzhen 518060 China

We provide the first demonstration of pure red emission in the visible light region via three-photon excitation in monodisperse N a3 ZrF7：Er nanoparticles （NPs） by using a laser operating in the telecommunication band. NPs of -22 nm in diameter are synthesized at 260℃ by the thermal decomposition method. The experimental results reveal that the Na3ZrF7：Er NPs exhibit pure red emission in the visible region under 1480 nm Laser excitation, and the emission intensity is significantly influenced by the Er3＋ ion concentration. The decay times of the 4S3/2 → 4F15/2 and 4F9/2 → 4F15/2 transitions of the Er3＋ ions at 540 and 655 nm, respectively, are reduced by increasing the Er3＋ ion concentration in the Na3ZrF7：Er NPs. The suppressed emission intensity result from the defect-related quenching effect： when trivalent Er3＋ ions replac tetravalent Zr4＋ ions, extra Na＋ ions and F- vacancies are formed to re-balance the charge in the Na3ZrF7 matrix. The emission color of the Na3ZrF7：Er NPs is related to the cross relaxation between Er3＋ ions. These results provide an important step toward more ef- fective biological imaging and photodynamic therapy by minimizing the scattering of the excitation light and increasing the penetration depth.

关键词： Decomposition Ions Laser excitation Light Nanoparticles Photodynamic therapy Photons

Novel Experimental Method in the Study of Double Rydberg States by laser Resonance excitation

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Chinese Journal of lasers 1997年第2期6卷 141-146页

作者： XU Xiangyuan HUANG Wen(Department of Modern Applied Physics, Tsinghua University, Beijing 100084, China) Tsinghua Univ Beijing China

We describe a novel experimental method by introducing sequential ionization with a pulsed and a strong constant electric field in a time-of-flight mass spectrometer. This method is applied to study laser-excited double Rydberg states of neutral ytterbium atom, with the ionic resonance background in the spectrum of the double Rydberg states of Yb being greatly suppressed.

关键词： atomic double Rydberg state Laser excitation field ionization

Displacement sensor based on polarization mixture of orthogonal polarized He-Ne laser at 1.15μm

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Chinese Optics Letters 2012年第3期10卷 73-76页

作者：赵正启张书练张鹏曾召利谈宜东李岩 State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision Instruments and MechanologyTsinghua University

Displacement sensor based on the polarization mixture and the cavity tuning of the orthogonal polarized He-Ne laser 1.15μm is presented.The power tuning curves of He-Ne laser are irregular,and it is difficult to measure the change in cavity length.The distortion of the curves is caused by the higher relative excitation compared with the He-Ne laser at 633 nm.In view of its potential for the wider displacement measuring range,a new method of displacement sensing is developed.Experiments show that displacement measuring stability based on the method of the polarization mixture is better than that of the power tuning curves. The displacement sensor achieves the measuring range of 100 mm,resolution of 144 nm,and linearity of 7×10- 6 .

关键词： Laser excitation Mixtures Polarization Sensors

Application of electric field ionization method to detect the high-lying Rydberg states of Eu I

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Chinese Optics Letters 2011年第5期9卷 5-7页

作者：谢军戴长建李鸣 Key Laboratory of Display Materials and Photoelectric Devices Ministry of Education School of Science Tianjin University of Technology

The 4f^76s（~9S）np 8 P J （J = 5/2, 7/2, 9/2） Rydberg series converging to the first ionization limit 4f 7 6s 9 S 4 of the Eu atom using the three-step Laser excitation and electric-field-ionization （EFI） method are studied. First, the Eu atom is excited from the 4f 7 6s 2 8 S o 7/2 ground state to the 4f 7 6s7s 8 S o 7/2 state through the 4f 7 6s6p 10 P 9/2 state by the first two dye lasers. Next, it is populated to many higher-n members of the 4f 7 6s（ 9 S）np 8 P J Rydberg series by the third dye laser whose wavelength is scanned within a certain range. Finally, the atom in these higher-n states is ionized by the external pulsed electric field. With the field strength up to 2 kV/cm, we can detect the atom in 4f 7 6s（ 9 S）np 8 P J states with n 40. With the given laser line width, the level energies of Rydberg states with n as high as 72 can be determined. We not only confirm the previous data on the 4f 7 6s（ 9 S） np 8 P J Rydberg series, but also extend the n-value assignment significantly by detecting more states.

关键词： Atoms Dye lasers Electric excitation Electric fields Europium Ionization Laser excitation

High-resolution photoacoustic microscope for rat brain imaging in vivo

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Chinese Optics Letters 2010年第6期8卷 609-611页

作者：杨孝全蔡鑫 Konstantin Maslov 汪立宏骆清铭 Britton Chance Center for Biomedical Photonics Wuhan National Laboratory for OptoelectronicsHuazhong University of Science and Technology Optical Imaging Laboratory Department of Biomedical EngineeringWashington University in Saint LouisSaint Louis63130-4899USA

A reflection-mode photoacoustic microscope（PAM） for rat brain imaging in vivo is constructed.A pulsed laser is used as an excitation source,and a focused ultrasound transducer is adopted to collect the photoacoustic signal.Raster scanning is applied to acquire three-dimensional（3D） data.The obtained measurements of the lateral and axial resolutions of the microscope are 45 and 15μm,respectively.The imaging depth in the chicken breast tissue is 3.1 mm at a signal-to-noise ratio（SNR） of 20 dB without any signal averaging.The imaging speed is 30 A-line/s.Experimental results in vivo demonstrate the capability of 3D imaging of the brain vessels of the rat after removing the skull.

关键词： Acoustic microscopes Laser excitation Photoacoustic effect Photoacoustic microscopy Pulsed laser applications Pulsed lasers Signal to noise ratio Ultrasonic transducers

Observation of wedge waves and their mode transformation by laser ultrasonic technique

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Chinese Optics Letters 2011年第2期9卷 66-68页

作者：贾静沈中华王丽娟袁玲 Faculty of Science Nanjing University of Science and Technology

Wedge waves （WWs） in wedges, including their dispersion characteristics and mode transformation, are investigated using the laser ultrasound technique. Pulsed Laser excitation and optical deflection beam method for detection are used to record WWs. Numerous WWs are detected by scanning the excitation laser along the wedge tip. Dispersions of WWs are obtained by using the two-dimensional （2D） Fourier transformation method, and different WW orders are revealed on the wedges. Mode transformation is determined by fixing the distance between the excitation and detection position, as well as by scanning the samples along the normal direction of the wedge tip.

关键词： Dispersion (waves) Fourier analysis Fourier transforms Laser excitation Ultrasonic testing Ultrasonics

Investigation of ultrafast electron dynamics of nickel film and micro-nano-structure film

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Chinese Optics Letters 2009年第7期7卷 650-652页

作者：金卫凤周明刘长隆王辉刘会霞任乃飞 Photonics Fabrication Science Center Jiangsu University

The electron thermalization and relaxation processes in ferromagnetic nickel thin film and micro-nano- structure film have been studied by measuring the transient change after excitation by a femtosecond laser pulse. The measurements indicate that the electron thermalization time is between 18 and 47 fs. This is somewhat faster than the value reported before. And the thermalization time of the micro-nano-structure film is much longer than the nickel film. We deduce that it is caused by the discontinuity of the electron band close to the Fermi level in the micro-nano-structure nickel film.

关键词： Electrons Laser excitation Metallic films Nanostructures Nickel Nickel alloys Pulsed laser applications

Two-photon imaging of lymphoma cells targeted by gold nanoparticles

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Chinese Optics Letters 2008年第12期6卷 879-881页

作者：屈晓超王晶姚翠萍张镇西 Life Science Research CenterSchool of Electronic Engineering Xidian University Key Laboratory of Biomedical Information Engineering of Ministry of Education Institute of Biomedical Analytical Technology and InstrumentationSchool of Life Science and TechnologyXi'an Jiaotong University

Gold nanoparticles （NPs） have highly efficient multi-photon-induced luminescence. In this paper, we record the two-photon images of gold NPs, lymphoma cell line Karpas 299, and Karpas 299 incubated with 30-nm-diameter gold NPs and ACT-1 antibody conjugates （Au30-ACT-1 conjugates） by using a multi-photon microscopy system. Due to the specific conjugation of ACT-1 antibody and cell membrane receptor CD25, gold NPs are only bound to the surface of cell membrane of Karpas 299. The luminescence intensity of gold NPs is higher than that of cells at 750-nm Laser excitation. By comparing the images of Karpas 299 cells incubated with and without gold NPs, it is found that by means of gold NPs, we can get clear cell images with lower excitation power. Their excellent optical and chemical properties make gold NPs an attractive contrast agent for cellular imaging.

关键词： Animal cell culture Cell culture Cell membranes Chemical properties Cytology Image enhancement Laser excitation Light emission Light sources Luminescence Nanoparticles Photons Scanning

Micro-Raman spectroscopy of single leukemic cells

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Chinese Optics Letters 2008年第12期6卷 938-940页

作者：蔡长美陈荣林居强李永增冯尚源 Key Laboratory of Optoelectronic Science and Technology for Medicine Ministry of Education of China Fujian Provincial Key Laboratory for Photonics TechnologyFujian Normal University

The Raman spectra from leukemic cell line （HL60） and normal human peripheral blood mononuclear cells （PBMCs） are obtained by confocal micro-Raman spectroscopy using near-infrared laser （785 nm） excitation. The scanning range is from 500 to 2000 cm^-1. The two average Raman spectra of normal PBMCs and carcinoma cells have clear differences because their structure and amount of nucleic acid, protein, and other major molecules are changed. The spectra are also compared and analyzed by principal component analysis （PCA） to demonstrate the two distinct clusters of normal and transformed cells. The sensitivity of this technique for identifying transformed cells is 100%.

关键词： Cell culture Infrared devices Laser excitation Nucleic acids Principal component analysis Raman scattering Raman spectroscopy Spectrum analysis