Vol. 34, No. 10 (1985)
1985, 34 (10): 1233-1240. doi: 10.7498/aps.34.1233
The critical phenomena of bistability is discussed on the basis of the relaxation equation of the nonlinear systems with a time-delayed feedback. We find that the critical slowing down at the edges of bistable region possesses consistency with the divergence of the time duration of intermittency. The critica1 exponent is 1/2. We also find that, different from the critical points at the bistable region edges, there are consistencies with the period-doubling bifurcation points and split bifurcation points at the cusp point (in cusp catastrophe model of bistability). The critical exponent is 1. The abo-ve-mentioned results possess universal properties. The computer experiments have been made in the liquid crystal hybrid optical bistable device. The results are in agreement with the analyses.
1985, 34 (10): 1241-1248. doi: 10.7498/aps.34.1241
Using intense pulsed laser beam of 5320 ? to excite the BDN dye solution inside the F-P interferometer, we have found the transient and intrinsic optical bistability effect. The various possible mechanisms to induce the refractive-index change of the sample medium and their relative contributions have been estimated; finally it is confirmed that in the duration of input laser pulse the refractive-index variation increases with time approximately in the form of semi-cubic parabola, and the main mechanism to cause this variation is the opto-thermal effect of the sample medium.
DETERMINATION OF THE RATIO OF THE SPIN ROTATION COUPLING CONSTANT TO THE SPIN EXCHANGE CONSTANT FOR THE K39Xe129VAN DER WAALS MOLECULE
1985, 34 (10): 1249-1260. doi: 10.7498/aps.34.1249
Optical pumping methods have been used to measure the ratio x of the spin rotation coupling constant to the spin exchange coupling constant of the K39Xe129Van der Waals molecule. The theory of these measuements is discussed in detail. The value x=γN/a= 4.8(1) is inferred from these studies.
1985, 34 (10): 1261-1269. doi: 10.7498/aps.34.1261
In this work, the vibrational energy transfer of organic molecule CH2C12 was studied with laser induced fluorescence method for the first time. The activation and deactiva-tion rate constants of modes ν3 and ν3/ν9 of pure CH2C12, as well as the effect of rare gases on the deactivation processes for ν3/ν9, were obtained. The relative propablities of energy transfer from ν3/ν9 vibrational modes of CH2Cl2 to translational degree of freedom were calculated by means of SSH theory for the collision relaxation processes of CH2Cl2-rare gas mixtures. A vibrational energy transfer channel in CH2C12 is also discussed.
1985, 34 (10): 1270-1279. doi: 10.7498/aps.34.1270
Starting from the unified theory of low-frequency fluctuation, dissipation, and relexation processes, we studied the ultrasonic absorption in the thermal activation pro-cess in glasses. The theory involves only a single relaxation time and differs from the theory of distributed relaxation times. Nontheless, it can explain the experimental cha-racteristics of the ultrasonic absorption in glasses and the universality of these charac-teristics independent of kinds of materials, which couldn't be interpreted by the pre-vious theory with the distribution of relaxation times.
1985, 34 (10): 1280-1290. doi: 10.7498/aps.34.1280
Some trial and error procedures are often used in the proccess of structure determination (calculating normalized structure factor, determining phase and builting molecular model) by the direct method. The present paper provides a procedure to calculate a trial molecular formula (TMF) on the basis of the diffraction data. Five unknown structures have been solved succesfully by means of the TMF. This method is helptul in extending the application of the direct method.
A ASED-MO STUDY OF THE MICRO MECHANISM OF ACTIVATION OF CO ADSORBED ON Ni(100)AND POISONING BY THE SUBMONOLAYER S ATOM
1985, 34 (10): 1291-1298. doi: 10.7498/aps.34.1291
Using an atom superposition and electron delocalization molecular orbital (ASED-MO) theory, the micro-mechanism of activation of CO adsorbed on Ni(l00) and of poisoning by submonolayer S atom is studied. CO is found to bond to the top site more strongly than on the fourfold site. When CO is adsorbed on the top site, it will get 0.72 e on its antibonding 2π orbital, and its dissociation energy will reduce from 11.1 eV for free CO molecule to 2.15 eV. If CO is adsorbed on the fourfold site, the electrons on its 2π orbital will be 1.22 e and dissociation energy 1.85 eV. It seems likely that CO adsorbed on fourfold site is more active. Our binding energy calculations have verified that one S atom adsorbed on Ni(l00) will inhibit 4 nearest top sites and 4 nearest fourfold sites from adsorbing CO molecule, but will not give any important affection on farther sites. These results support the idea that the dominant effect of adsorbed S atom is "structural effect". These "blockage" effect by the adsorbed S atom, i.e. the reduction of the active sites, and some other factors, result in the poisoning of Ni sur-faces by submonolayer S atom.
INVESTIGATION OF CO AND NO CHEMISORPTION ON THE Ⅷ GROUP TRANSITION METAL SURFACE BY Xα-DV METHOD(Ⅰ)——ELECTRONIC STRUCTURE OF CHEMISOPTION OF CO ON Rh(111) SURFACE
1985, 34 (10): 1299-1305. doi: 10.7498/aps.34.1299
In this paper, the electronic structure of chemisorption of CO on Rh(lll) surface (θ≤l/3) has been calculated by the method of the self-consistent Hartree-Fock-Slater molecular cluster. The variation of the energy levels and total energy with respect to the vertical distance of the CO molecule above this surface is obtained. The optimized bond distance determined from the total energy curve is 1.85 ?, which is quite close to experimental result 1.95±0.1?. The binding energy is 0.98 eV, which is smaller than the experimental adsorption energy of 1.3 eV. The total density of states with above bond distance is calculated and it is in good agreement with the UPS result considering final state and relaxation effect. The bonding and antibonding character for the CO valence level have also been studied by analysis of the variations of the molecular eigenvalues when the CO molecule approaches the surface. The charge transfer for CO chemisorption on transition metal Rh is investigated through a Milliken population analysis and the analysis of coefficients of cluster wavefunction which is expanded by using CO molecular wavefunction. This charge transfer causes the activation of absorbed CO molecules.
INVESTIGATION OF CO AND NO CHEMISORPTION ON THE Ⅷ GROUP TRANSITION METAL SURFACE BY Xα-DV METHOD(Ⅱ)——CHEMISORPTION OP NO ON PD(111) SURFACE
1985, 34 (10): 1306-1314. doi: 10.7498/aps.34.1306
The Chemisorption of NO on Pd (111) surface is calculated using Xα-DV method. It's electronic structure, including spectrum of the ground state valence levels, density of states, and the charge transfer between adsorbate and substrate, is obtained. The interaction between adsorbed NO molecules is included in our calculations. The results of DOS are in good agreement with UPS, supporting the LEBD structural analysis, and the adsorption height is determined to be 1.27 ?. Our theoretical results have verified that the interaction between NO is rather important in the chemisorption of NO on Pd surfaces. The activation of adsorbed NO on Pd(lll) is discussed. It is evident from our results that the charge transfer between adsorbed NO and substrate is similar to CO adsorption on transition metal. Finally, we found that the adsorption of NO does not significantly affect the valence band of Pd.
1985, 34 (10): 1315-1321. doi: 10.7498/aps.34.1315
The measurement 011 the sterochimical structure of H3+ molecular ion is reported. It makes use of the Coulomb explosion of a fast molecular ion. It is shown that the structure is equilaterally triangular in shape. The mean value of most probable inter-proton separations is found to be 0.98±0.03?. A set of high resolution experimental arrangment of ours is also described.
PRESSURE EFFECT ON THE STABILITY AND PHASE TRANSFORMATION OF THE ε-PHASE IN SPLAT QUENCHING Fe-C-Sb ALLOY
1985, 34 (10): 1322-1326. doi: 10.7498/aps.34.1322
Pressure effect on the phase transformation process of the ε-phase of splat quenching Pe-C-Sb alloy has been investigated by using X-ray powder photography. The experimental results show that high pressure will not only increase the stability of the ε-phase remarkably but also change its phase transformation process. At 4.7 GPa, as the temperature of stability of ε-phase increases to 450℃, a new metastable phase of orthorhombic structure, being absent at normal pressure, will appear. By raising annealing temperature to 560℃, the orthorhombic metastable phase begins to transform into Fe3C which will decompose into carbon (graphite) and γ-Fe on further increasing annealing temperature to 800℃. At this time, the alloy is composed of C (graphite), γ-Fe, Sb and another unknown phase.
THE CRYSTALLIZATION PROCESS OF METGLASS (Fe0.1Co0.55Ni0.35)78Si8B14 AND THE EFFECT OF HIGH PRESSURE (Ⅱ)——The Crystallization Temperature and The Crystallization Activation Energy
1985, 34 (10): 1327-1335. doi: 10.7498/aps.34.1327
In this paper, the pressure dependence of the crystallization temperature Tx and the crystallization activation energy △EX of metglass (Fe0.1Co0.55Ni0.35)78Si8B14 werestudied by measuring the electrical resistivity in-situ under pressure up to 3 GPas. It was found that application of high pressure not linearly, even not monotonicaly riases the Tx, as usually described in literatures for pressure dependence of Tx in metglasses, but shows some local detours on Tx vs. P curve in a general rising tendency. △Ex shows same behaviour analogous to that of Tx as the pressure rises. An analytical discussion indicates that pressure promotes the nucleation process and restrains the diffusional growing up of the crystallized nuclei on heating the metglass. As a combined result of the mutual contrary effects of pressure on nucleation activation energy a,nd diffusion activation energy, it gives rise the above non-monotonic rising behaviour of △Ex and Tx of the metglass studied. In addition to △Ex, pressure may also markedly affect the preexponential factor and produces a considerable change on crystallization temperature.
1985, 34 (10): 1336-1341. doi: 10.7498/aps.34.1336
The structure of amorphous MoS3 as the cathode materials in lithium batteries was studied by using X-ray diffraction method and X-ray photoelectron spectroscopy. The results revealed that the structure of amorphous MoS3 is built by homogeneously eandomly stacking of the MoS2 basic unit S-Mo-S sand wich layvs and the amorphous sulphus chains Sn.
The (4+1)-dimensional cosmological model discussed in this paper is a direct product of the usual 4-dimensional spacetime and a. 1-dimensional compaetified internal space. The energy density of the 4-dimensional spacetime is supposed to be dominated by incoherent radiation and the energy-momentum tensor of the internal subspace is a step function. By solving the 5-dimensional Einstein field equations without cosmolog-ical term we get the de-Sitter solution to describe the usual spacetime and at a certain time it changes to the radiation-dominated solution for standard model, and the size of the internal subspace changes with time in a form of oscillation with amplitude attenuating and then contracts to a constant.
1985, 34 (10): 1348-1353. doi: 10.7498/aps.34.1348
Instability and chaos in a three-mode He-Ne (6328?) laser was studied by varying discharge current and cavity length. Period doubling, two-frequency and intermit-tency routes to chaos have been observed.
1985, 34 (10): 1354-1358. doi: 10.7498/aps.34.1354
The methyl P-hydroxybenzoats cryslal is a organic pyroelectric crystal. A thorough experimental study has been carried out on its pyroelectric effect, electric condutance, hysteresis loop and other relevant properties.
1985, 34 (10): 1359-1362. doi: 10.7498/aps.34.1359
It is clarified that the interaction picture introduced in CTPGF ought to be the incoming one and the perturbation expansion of CTPGF to be developed also in this sense.
The solid solution AlxGa1-xP(0≤x≤0.64) has been investigated by XPS and ABS.The experimental results show that the binding energy of P21, core level decreases and the top of the valence band recedes with increasing Al-content. Moreover the weak Auger peaks of GaP have been identified and clarified.
1985, 34 (10): 1368-1372. doi: 10.7498/aps.34.1368
Using Sn-I-Sn-I-Sn-I-Sn triple tunnel junctions, some spatial inhomogeneous states in superconducting tin films were observed under strong phonon injection.
The electronic structure and the X-ray photoemission spectrum for VPd3 were calculated using the self-consistent LMTO method. The general feature and the peak positions of the density of states were in reasonable agreement with Williams et al. Contrary to their result μs～1.4μB for VPd3, the calculated Stoner parameter for VPd3 is 1.04, which indicated that VPd3 may be considered as one of the weak itinerant magnets likely. Nevertheless, a discrepancy between ours and Burmester et al., who found no evidence for magnetic ordering in VPd3 down to 1.6 K, remained to be solved.