Resonance frequency shifts due to radiation fields in the laser-cooled cesium fountain frequency standard, such as the frequency shifts due to microwave spectral impurity, Bloch-Siegert effect, neighboring π transitions, Stark effect, blackbody radiation and Majorana transitions, are investigated, with formulas for evaluating the shifts presented. The magnitudes of the shifts and their uncertainties are evaluated and their effects on the accuracy of the standard are analyzed. In addition, approaches for reducing the shifts and uncertainties are proposed in order to improve the accuracy of the standard. The results obtained here might be of great help for designing the laser-cooled cesium fountain frequency standard and evaluating the accuracy of the standard.

According to edge-wave diffraction theory, we have analyzed and compared the edge-wave diffraction intensity of gaussian(n=2)、parabolic(n=1,2) functions and linear taper variable reflectivity mirrors. Numerical results show that gaussian and super-gaussian reflectivity mirrors can reduce the edge-wave diffraction intensity more effectively, and obtain zeroth-order approximate geometrical optical fields.

Several properties of Bose-Einstein condensed atoms confined in a double well potential(DWP) are investigated, which include the tunneling effect, interference of the condensed atoms and the dynamics of the atom-standing wave laser field system. It is shown that, in such a DWP, the average number of condensed atoms in the two traps is still same in presence of tunneling effect, this ensures the visibility of interference fringes of atoms. The interference fringes are closely related to the difference and sum of atomic wave packet of the two traps. Moreover, the present result manifests that the tunneling effect can obviously affect the dynamics properties such as wave function, energy spectrum of the atom-standing wave laser field system.

Chaos control of acousto-optical bistable system is investigated numerically using periodic external perturbation feedback. Chaos state controlled to fixed point and periodic orbits can be obtained by adding periodic perturbation signal with proper amplitude and frequency. The efficiency of the above method is proved by experiment.

he second-order squeezing and the second-order coherence of an initial two-mode squeezed vacuum field in the Jaynes-Cummings model are studied by means of the quantum theory. The influence of squeezing parameters on the nonclassial properties of light are discussed.

In this paper, the bunching and antibunching effects of the photon in the two-hoton process with two-level atomic mixed-state are studied by means ofthe time-volution operator method and numerical calculation. The results show that thequantum collapse and revival properties do not depend on the mixing extent of the atomicinitial state. The antibunching effect of the radiation photons is displayed periodicallyas 0.97≤|S|≤1;with the increasing of the mixing extent of the atomic initial state,the average value of the second-order correlation function g⁽²⁾(0) will become larger,and the characteristics of radiative photons is getting far from antibunching effects.

It is compulsory to realize the accurate control of the growth process of each material layer before a ZnSe-based laser diode could be fabricated, such as crystal quality control, doping level control and growth rate control. ZnSe is the fundamental material for blue/green laser diodes. Reported here are the primary results of an attempt on the crystal quality control, the doping level control and the growth rate control of ZnSe by MBE technology.

We have demonstrated the theory of utilizing internal two-photon-induced light absorption of semiconductor GaAs to accomplish Q-switched pulse lengthening. The rate equations are solved and the experiments are performed with an electrooptic Q-switching Nd:YAG laser with a GaAs sample in its cavity. As predicted by the theory that the output intensity and output energy both decrease and pulse length increases as compared with the normal Q-switched case. We were able to obtain pulses as long as 1～μs.

In this paper, the XeClexcimer laser excited by magnetically confined discharge is studied in both theory andexperiment, the results are compared and analyzed under the condition of Ar or He buffergas.

In this paper, the some main interference source that cannot result in noramal operation of double pulses Q-switch laser is described and analysed, the ten methods for solving the problem of anti-interference are provided for the double pulses Q-switch laser system．

We have studied theresonant two-photon ionizaition (R2PI) spectra of van der Waals complexes p-C6H4F2NH3...(ND3)through the S1←S0 transition withmass selectivity. Spectal analysis shows that the stretching frequencies of the complexesis about 86cm-1. From the photodissociation energy, we estimated the bond energy of the complexp-C6H4F2…NH3 in the S1 and S0 states. Abinitio calculation for p-C6/H4/F2/…NH3/ gives the following geometry: the N atom of NH3is located on the symmetry axis (Z-axis) and 0.353～nm above the benzene ring;the C3 axis of NH3is at an angle of 52.5° with the Z-axis of p-C6H4F2 withone of the hydrogen atoms pointing towards the benzene ring;the rotation of NH3around the Z-axis is nearly free. The calculataed bond dissociation energy and theprediction of internal rotation are consistent with our experimental results.

By using crossedmolecular beam apparatus, the visible chemiluminescence spectrum were investigated for thereaction F atoms with silane. The emission spectra of HF(3,0)、(4,0)、(5,1)、(6,2)，SiF(A-X) and Si(A-X) transitionwere observed. The relative vibrational state distribution of SiF(A) were obtained by thecomputer simulation. Experimental results indicated that the reaction F with silaneproceeds via a consecutive hydrogen-stripping process.

The method forextracting NO2 concentration from the data obtained by measurement of Sunspectra was given in this paper. The NO2 concentration about (1～4)×1016 moleculecm2in the atmosphere at suburb of Hefei city was obtained in agreement with that measured byother instrument.

A novel apparatus forthe studies of transient absorption spectroscopy and photo-induced reaction dynamics wasdeveloped recently. The unique characters was outlined as follows. A wide frequency-tunable laser system (4μs～200nm)with low flux was used as photolysis source. Transient species produced by laserphotolysis andor photochemical reactions can be detected by transient absorption spectra.Dynamic behavior involving radical reaction have been proved by this equipment.

Namometer sized a-Si3N4particles of 10～nm in average diameter were obtainedby Laser Induced Chemical Vapor Deposition (LICVD). The spectra of UV absorption andfluorescence of a-Si3N4 particles in different colloids weremeasured. Six fluorescent peaks from 3.0eV to 4.1eV were found for the first time. According to the absorption andfluorescence spectra of the particles, we studied their energy level structure. We alsodemonstrated that silicon dangling bond ≡Si0 plays a dominant role in the spectrum character fornanometer a-Si3N4 particles.

In this paper, a systemused to measure atmospheric optical parameters including atmospheric structure constant ofrefractive index, temperature spectrum etc. is presented. This system is made up oftemperature sensor, atmospheric parameter sensor, microcomputer, microcomputer network andthe single-chip system. The data can be automatically collected, processed, saved anddisplayed. Some results of this system are also discussed in this paper.