Sonochemical reduction of carbon dioxide

Sonolysis of carbon dioxide dissolved in water was performed from a standpoint of reducing this material in atmosphere. During one hour of sonication, the amount of CO2 decreased to about half at 5 degrees C under CO2-Ar atmosphere. The decreasing rate for CO2 followed the order Ar > He > H2 > N2 and it was down with increasing temperature in the range of 5-45 degrees C. The most favorable concentration for reducing CO2 was 0.03 (mole fraction of CO2 in gas phase). This concentration in gas phase means an equal mixture of CO2 and Ar in water, because CO2 is more soluble than Ar. Since carbon dioxide dissolved in water would be partly ionized, the roles of ions on the sonolysis were also examined. Gaseous reaction products were CO, H2 and a small amount of O2. Carbon monoxide and hydrogen might be obtained from CO2 and H2O by sonolysis, respectively. Both gases are fuel and react each other to C1 compounds such as methanol, and so on. Therefore, irradiation of ultrasonic waves should be an important technique for reducing CO2.     

Spectral anomalies of the light-induced drift of rubidium atoms caused by the velocity dependence of transport collision frequencies

The spectral features of the light-induced drift (LID) velocity for rubidium atoms (⁸⁵Rb and ⁸⁷Rb) in an argon buffer medium and in binary buffer mixtures of noble gases (Ne + Ar, Ne + Kr, Ne + Xe, He + Ar, He + Kr, and He + Xe) have been investigated theoretically. A strong temperature dependence of the spectral shape of the LID signal for Rb atoms in an Ar atmosphere is predicted in the temperature range 450 K < T < 800 K. It is shown that the anomalous LID of Rb atoms in binary buffer mixtures of noble gases can be observed at almost any temperature (including the room one) depending on the fractions of neon or helium in these mixtures. The results obtained enable a highly accurate testing of the interatomic interaction potentials used to calculate the drift velocity for anomalous LID in LID experiments.     

Effect of dissolved gases in water on acoustic cavitation and bubble growth rate in 0.83 MHz megasonic of interest to wafer cleaning

Changes in the cavitation intensity of gases dissolved in water, including H₂, N₂, and Ar, have been established in studies of acoustic bubble growth rates under ultrasonic fields. Variations in the acoustic properties of dissolved gases in water affect the cavitation intensity at a high frequency (0.83 MHz) due to changes in the rectified diffusion and bubble coalescence rate. It has been proposed that acoustic bubble growth rates rapidly increase when water contains a gas, such as hydrogen faster single bubble growth due to rectified diffusion, and a higher rate of coalescence under Bjerknes forces. The change of acoustic bubble growth rate in rectified diffusion has an effect on the damping constant and diffusivity of gas at the acoustic bubble and liquid interface. It has been suggested that the coalescence reaction of bubbles under Bjerknes forces is a reaction determined by the compressibility and density of dissolved gas in water associated with sound velocity and density in acoustic bubbles. High acoustic bubble growth rates also contribute to enhanced cavitation effects in terms of dissolved gas in water. On the other hand, when Ar gas dissolves into water under ultrasound field, cavitation behavior was reduced remarkably due to its lower acoustic bubble growth rate. It is shown that change of cavitation intensity in various dissolved gases were verified through cleaning experiments in the single type of cleaning tool such as particle removal and pattern damage based on numerically calculated acoustic bubble growth rates.     

Sonocatalytic facilitation of hydroxyl radical generation in the presence of TiO2

The generation of hydroxyl (OH) radicals was investigated during ultrasonic irradiation and in the presence of TiO(2). The effect of TiO(2) on an ultrasonic system's oxidation power was evaluated by examining the oxidation of salicylic acid. The generation of the salicylic acid derivatives, 2,3-dihydroxybenzoic acid (DHBA) and 2,5-DHBA, was measured by high-performance liquid chromatography coupled with electrochemical detection under different experimental conditions. The presence of TiO(2) enhanced the generation of DHBA during ultrasonic irradiation, thus indicating a higher oxidation power in the ultrasonic system. Al(2)O(3) also increased the generation of DHBA during irradiation; however, the effect of TiO(2) was found to be higher than that of Al(2)O(3). The addition of OH radical scavengers such as dimethylsulfoxide (DMSO), methanol and mannitol significantly suppressed the production of DHBA, and DMSO was found to have the highest suppressive effect among all scavengers. The effects of dissolved gases on the generation of OH radicals were further studied, and their power was found to be in the order Xe > Ar > O(2) > N(2). The degassing of the irradiation solution completely suppressed the generation of OH radicals. These results indicate that the presence of TiO(2) accelerates the generation of OH radicals during ultrasonic irradiation, and that the process may be mediated through the induction of cavitation bubbles in irradiating solutions.     

Ultrasound liberates nitric oxide (NO) from the caged NO compound N,N'-bis(carboxymethyl)-N,N'-dinitroso-p-phenylenediamine sodium salt

To determine whether nitric oxide (NO) can be released from a cage compound N,N'-bis(carboxymethyl)-N,N'-dinitroso-p-phenylenediamine sodium salt (BNN 5 Na), we sonicated different concentrations of BNN 5 Na solutions containing an NO spin trap, (MGD)2Fe2+, and then measured (MGD)2Fe2+-NO signal using electron paramagnetic resonance (EPR). We also investigated the role of cavitation by saturating the solutions with Ar, He or Xe gases before sonication. The result showed that ultrasound can liberate NO from caged NO compound at rates highest with Xe and lowest with He. These results suggest that high-temperature due to cavitations induced by ultrasound are capable of releasing NO from caged NO compounds. This finding also opens up to a new possibility for the use of ultrasound in a controlled release of active compound (e.g. drug) from its caged form for therapeutic purposes.     

Li-和Na-单电子解离过程的研究

采用交叉束方法 ,利用负离子源产生的 3— 19keV的Li- 和Na- 轰击惰性气体靶He ,Ne和Ar ,通过静电偏转和位置灵敏探测器区分碰撞后中性粒子束和负离子束 ,测量了不同碰撞系统的中性粒子计数与相应入射负离子计数的比值R(E) ,并得到R(E)与入射负离子能量、负离子种类和靶原子种类的关系. The count ratios R of the neutralized atoms of final state to projectiles Li -and Na -in collision with He, Ne and Ar are measured in the energy range of 3-19 keV. It is found that the count ratios R increase slowly with the collision energy in whole experimental energy range for He, Ne and Ar. For Li -→He, Ne, Ar Collisions, R(He)≈R(Ar)>R(Ne), and for Na -→He, Ne, Ar Collisions, R(He)>R(Ar)> R(Ne).     

液体中溶解气体的普适分析方法-声致发光法

液体中溶解气体的量的分析一直是分析化学中的难题。迄今为止,只是发展了水体中溶解氧的化学分析与仪器分析方法,而其他的气体如N2,CO2,CH4的分析方法至今仍很缺乏,特别是液体中溶解的稀有气体,如：Ar,He,Ke的分析方法至今仍然是空白,文章介绍了声致发光分析气体溶解于液体（包括非水溶液）的新方法。     

Impact of bubble coalescence in the determination of bubble sizes using a pulsed US technique: Part 2 – Effect of the nature of saturating gas

Knowledge on cavitation bubble size distribution, ambient radius of bubbles is of interest for many applications that include therapeutic and diagnostic medicine. It however becomes a hard quest when increasing the ultrasonic frequency, when direct observation of bubble dynamics is no longer possible. An indirect method based on the estimation of the bubble dissolution time under pulsed ultrasound (362 kHz) is used here under optimized conditions to derive ambient radii of cavitation bubbles in water saturated with He, Ar, Xe, O₂, N₂ and air: 3.0 µm for Ar, 1.2 µm for He, 3.1 µm for Xe, 2.8 µm for O₂, around 1 µm for N₂ and air. If the pulse on-time is increased, bubble coalescence occurs, the extent of which is rather limited for Ar but extremely high for He or N₂.     

液态低沸点气体的表面张力

利用双毛细管法测定了液氮沸点温度下液氮的表面张力。用非线性方程γ＝γ&#176;（１－Ｔ／Ｔｃ）＾ｎ描述了液态Ｎ２、Ｏ２、ＡｒＸｅ、Ｈ２、Ｎｅ、Ｈｅ、Ｆｅ和Ｋｒ的表面张力与温度的关系，并采用一元性回归的方法拟合了上述各流体的参数γ&#176;和ｎ，准确度高于文献值，说明方程能正确表达表面张力与温度的关系。这些数据有利于对上述低沸点气体进行准确的热力学计算。     

Is the critical Reynolds number universal?

This paper is devoted to checking whether the critical Reynolds number is universal in identical conditions for the flow of different fluids. The laminar-turbulent transition in a circular pipe flow has been tested experimentally. The flows of inert gases (He, Ne, Ar, Kr, Xe), molecular gases (N₂, CO, CO₂, SF₆), and two similar liquids (H₂O, D₂O) have been tested. A considerable, up to 40%, difference in critical Reynolds numbers was observed. The possible reasons for nonuniversality of the critical Reynolds number are discussed.     

A uniform quasi-classical description of radiative transitions for asymmetric rare-gas atom-atom collisions

The uniform quasi-classical approximation [14] is used to describe the optical spectra formed during asymmetric collisions between atoms of rare gases in which one of the atoms is in a metastable state. We consider the reactions He(2¹S) + Ne → He(1¹S) + Ne + ?ω and Ar(³P₂) + He → Ar(¹S) + He + ?ω, in which the optical transition mechanisms are typical of most rare gases. Quasi-molecular terms of excited states and radiative widths calculated in a unified semiempirical approach are used. Spectral characteristics are calculated for thermal collision energies in the entire frequency range, including the center and both wings of the forbidden line. For the blue wing, our results are consistent with the widely used Condon approximation at collision energies E ≥200 cm^?1. At lower collision energies and in the region of the red wing and center of the forbidden line, the spectral distributions that cannot be described in the Condon approximation are reproduced in the uniform quasi-classical approximation. Comparison with quantum-mechanical calculations by the strong-coupling method confirms the high accuracy of the uniform quasi-classical approximation in the entire range of radiation frequencies.     

Production of copper vapor in a pulsed hollow cathode discharge

Spectral emission from a pulsed Cu hollow cathode was investigated in relation to discharge current to gain information on the density of the sputtered Cu vapor and on the persistence time of the metastable and ground-state atoms. The cathode was excited with 250 μsec discharge pulses at current densities up to 1 A/cm², using He, Ne and Ar as buffer gases. The intensities of the emitted Cu I lines were found to depend strongly on the simmer current. In atmospheres of Ne or Ar, the intensities of the resonance lines exhibited characteristic maxima during the initial 20 μsec of the discharge pulses. The density of the sputtered Cu atoms was determined by absorption measurements using a second Cu hollow cathode as alight source.     

NeMu* chemiluminescence: Radiolysis effects in gases

Near-infrared chemiluminescent emission from NeMu^*, the analogue of the Rydberg molecule NeH, has been observed in Ne, Ar, and Ne/Ar gas mixtures. Three temporally distinct features were observed: First, a large sharp emission peak at time zero, observed in all gases (Ne, He, N₂, Ar), is assigned to scintillation light during muon thermalization, probably caused by spur electrons. Second, a lowintensity broad region observed in all gases is attributed to e⁺ from muon decay. Finally, NeMu in 1–6 atm Ne with 0.1–2 torr Ar appeared as a high intensitydelayed emission, whose width and intensity depended linearly on the Ar concentration. Its wavelength spectrum from 680–960 nm was measured. Although questions remain as to how NeMu^* is formed, the precursor is likely Ne ⁺. Possible electron donors include metastable Ar^* (³ P ₂ or³ P ₀) and long-lived free (spur) electrons.Contribution from CEMAID, Center of Excellence in Molecular and Interfacial Dynamics; the financial support afforded by participation in Canada's National Centers of Excellence program is greatly appreciated.     

Spectroscopic diagnostics of barrier discharge plasmas in mixtures of zinc diiodide with inert gases

The spectral characteristics of the emission of gas discharge atmospheric pressure plasmas in mixtures of zinc diiodide vapor with inert gases (He, Ne, Ar, Kr, and Xe) are investigated. The formation of a gas discharge plasma and the excitation of the components of a working mixture were performed in a high-frequency (with a repetition frequency of sinusoidal voltage pulses of 100 kHz) barrier discharge. The gas discharge emission was analyzed in the spectral range 200–900 nm with a resolution of 0.05 nm. Emission bands of ZnI(B-X) exciplex molecules and I₂* excimer molecules, lines of inert gases, and emission bands of XeI* exciplex molecules (in Xe-containing mixtures) were revealed. It is ascertained that the strongest emission of ZnI* molecules is observed in ZnI₂/He(Ne) mixtures. The regularities in the spectral characteristics of the gas discharge plasma emission are considered.     

Preliminary results on the effect of power ultrasound on nitrogen oxide and dioxide atmosphere in nitric acid solutions.

The effect of ultrasound (20 kHz, 3 W cm-2) on the kinetics of HNO2 and H2O2 formation was investigated in a 1 M HNO3 medium for NO2-Ar and NO-Ar gas mixtures in various volume fractions (f(NO2) < 1.7 vol% and f(NO) < 1.1 vol%, respectively). The H2O2 formation rate measured in 1 M HNO3 in the presence of N2H5NO3 was observed to be much lower than that of HNO2 without N2H5NO3, and was relatively independent of the NO2 or NO gas volume fractions in the argon atmosphere. The HNO2 formation rate increased under ultrasound, and was higher with NO than with NO2. The induction period observed without ultrasound disappeared when ultrasound was applied. The first step in the sonochemical mechanism of HNO2 formation in the presence of NO2 involves thermal decomposition of NO2 into NO within the cavitation bubble. In the second step of HNO2 formation, NO reacts either with HNO3 in the cavitation bubble, or with NO2 in the cavitation bubble or at the bubble/solution interface.     

Kinetics of nitrous acid formation in nitric acid solutions under the effect of power ultrasound

Sonochemical nitrous acid formation was investigated in 0.1-4.0 mol dm(-3) aqueous nitric acid solutions under the effect of power ultrasound with 20 kHz frequency. HNO2 steady-state concentration was obtained under long-time sonication; the excess HNO2 formed is decomposed and evoluted from the solution as NO and NO2 gases. The HNO2 steady-state concentration and the HNO2 initial formation rate depend linearly on the HNO3 concentration and acoustic intensity (1.8-3.5 W cm(-2)) and decrease with rising temperature in the range 21-50 degrees C. The HNO2 formation rate depends on the type of saturating gas as follows: Ar > N2 > He > air. NO and O2 are the major gaseous products of HNO3 sonication. The NO2 accumulation of in the gas phase is observed only when the decomposition of HNO2 formed becomes noticeable. The gaseous products formation rates depend on the HNO3 concentration, acoustic intensity and the type of saturating gas. The mechanism of HNO2 sonochemical formation is assumed to be the thermal decomposition of HNO3 in the gaseous vicinity of collapsing bubbles or in the overheated liquid reaction zone surrounding the cavitational bubbles.     

Content and Isotope Ratios of Noble Gases in Congelation Ice of Lake Vostok

Isotope ratios of noble gases (He, Ne, Ar) were studied in samples collected by degassing of cores of water frozen over a glacier of Lake Vostok. The gases were collected into glass retorts during three days of degassing of cores, which have just been extracted from the borehole. Within the error, the isotope ³He/⁴He ratios of 0.28 ± 0.08 R_A (R_A = 1.38 × 10^–6 is the ratio for air) correspond to those from [1]. The ⁴He/²⁰Ne and ⁴⁰Ar/³⁶Ar ratios (12.4 ± 4.6 R_A and 1.0074 ± 0.0023 R_A, respectively) exceed their contents in air (⁴He/²⁰Ne_A = 0.29; ⁴⁰Ar/³⁶Ar_A = 298.6) and may indicate some contribution of terrigenous gas to the gaseous balance of the lake, as well as the high content of ancient ground waters in the lake. The ³He/⁴He ratio of 0.28 R_A means low mantle ³He flux typical of continental platforms far from active rift zones.     

低能束箔光谱研究

本文简要介绍近代物理所开展的低能束箔光谱学研究情况以及获得的实验数据（包括Ｎ、Ｏ、Ｎｅ、Ａｒ、Ｆｅ和Ｃｕ等的激发光谱和能级寿命）,并讨论了实验的精度． In this paper, we describle the experiments at IMP and the beam-foil experimental data(including spectra, lifetimes of He, N, O, Ne, Ar, Fe and Cu ions). The accuracy estimated is also given here.     

A comparison of self broadening and shift of helium,neon and argon emission lines

Self broadening (van der Waals and resonance) and shift of Ne emission lines and van der Waals broadening and shift of He emission lines have been measured using a high pressure (0.5–3.0 atom), low current discharge. These results are compared with previous measurements in Ar and He to obtain a complete comparison of self broadening and shift of He, Ne and Ar emission lines. Oscillator strengths for the resonance transitions are obtained from the resonance broadening coefficients. The trend of the van der Waals broadening coefficients for the three noble gases is correctly predicted by a theory due to HINDMARSHet al.⁽⁴⁾ in which a Lennard-Jones potential is used in the impact theory formalism. The measured line shifts cannot be accounted for by this theory and reflect the need for more accurate quantum mechanical calculations.     

核泵浦气体激光研究

本文介绍了利用核能激励Ｎｅ、Ｈｅ、Ｘｅ、Ａｒ等气体产生激射这一领域内所取得的成果．利用￣（２３８）Ｐｕ源激励Ｎｅ、Ｈｅ－Ａｒ、Ｎｅ－Ｈｅ、Ｎｅ－Ｈ＿２体系,测到了Ｈｅ、Ｎｅ、Ａｒ、Ｈ＿２对Ｎｅ（２ｐ＿１）态的倒空速率常数．利用３００￣＃稳态堆激励Ｈｅ－Ｈｅ体系,测得其增益为２×１０￣（－２）／ｃｍ．在ＣＦＢＲ－Ⅱ脉冲堆上进行了Ｈｅ－Ａｒ－Ｘｅ体系的激射实验,测到了激光信号,其波长为１．７３μｍ,激光功率约为１０ｍＷ． The results of nuclear pumping Ne, He, Ar, Xe are introduced in this paper.￣(238)Pu was used to exite Ne, Ne-Ar, Ne-He, Ne-H_2 systems. The elimination rate constantsof Ne (2p_1 ) by Ne,He,H_2,Ar were measured. 300￣# stable reactor was used to encourage HeNe system, the gain measured was 2 ×10￣(-2)/cm. Lasing experiment of He-Ar-Xe system wasdone on CFBR-Ⅱ pulse reactor, lasing sign was measured, λ=1.73μp, lasing power wasabout 10 mW.