共查询到20条相似文献,搜索用时 15 毫秒
1.
A chemical laser has been constructed in which simultaneous output is obtained from both CO and CO2 laser species at 5 and 10 μm, respectively. Excitation of CO2 is via energy transfer from vibrationally excited CO (CO2) produced in the photolytically initiated reaction: O + CS → CO2 + S. Gain measurements at the CO2 laser frequencies are also reported. 相似文献
2.
A frequency-doubled cw dye laser has been used to determine the initial vibrational distribution of CS formed in the reaction O + CS2 → CS + SO by application of laser-induced fluorescence. The A15—X1σ+ system of CS was excited, and rotationally resolved spectra of a number of bands measured. The vibrational distribution found for υ = 0–2 is 1.0:0.27:0.11, yielding a value of 6% for the fraction of reaction exoergicity entering vibration of this product. No evidence of high product rotational excitation wss detected for a reaction pressure 5 × 10?3 Torr. 相似文献
3.
The relative rates at which O + CS → CO + S populates individual vibrational levels of CO have been determined (a) from infrared chemiluminescence experiments, and (b) by using a cw CO lawer to measure CO vibrational distributions produced when mixtures of CS2 + O2 are flash photolysed. 相似文献
4.
Ian L. Alberts Nicholas C. Handy Emmanuel D. Simandiras 《Theoretical chemistry accounts》1988,74(5):415-428
The structure and harmonic vibrational frequencies of several weakly bound complexes formed by HF are reported. Theab initio MP2 approach is used with large basis sets for the optimisation of geometries and the determination of harmonic frequencies. COHF and OCHF are examined; both are found to be minima, with the latter being the dominant structure. The linear OCOHF andT shaped OCOFH are studied, but only the linear structure is a minimum. N2OHF has two minima on the surface corresponding to bent NNOHF and linear ONNHF structures. 相似文献
5.
6.
Prof. Dr. Carsten Jenne Marc C. Nierstenhöfer Dr. Valentin van Lessen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(10):3288-3291
The hydride-bridged silylium cation [Et3Si−H−SiEt3]+, stabilized by the weakly coordinating [Me3NB12Cl11]− anion, undergoes, in the presence of excess silane, a series of unexpected consecutive reactions with the valence-isoelectronic molecules CS2 and CO2. The final products of the reaction with CS2 are methane and the previously unknown [(Et3Si)3S]+ cation. To gain insight into the entire reaction cascade, numerous experiments with varying conditions were performed, intermediate products were intercepted, and their structures were determined by X-ray crystallography. Besides the [(Et3Si)3S]+ cation as the final product, crystal structures of [(Et3Si)2SMe]+, [Et3SiS(H)Me]+, and [Et3SiOC(H)OSiEt3]+ were obtained. Experimental results combined with supporting quantum-chemical calculations in the gas phase and solution allow a detailed understanding of the reaction cascade. 相似文献
7.
Explosions occur when O3 and H2CO are mixed in a fresh vessel, even in the presence of several hundred torr of N2 or O2. However, in an aged vessel the reaction is well behaved. The reaction between O3 and H2CO was studied at room temperature in an aged vessel in the presence of about 400 torr of either N2 or O2. The initial rate of O3 decay in the presence of N2 is about 103 times faster than in the presence of O2, and very small amounts of O2 quickly reduce the initial rate of O3 decay in the N2 case. A chain mechanism is postulated to account for the results in which chain initiation can occur both by thermal decomposition of O3, followed by reaction of O(3P) with H2CO to produce HO and HCO, as well as by which may occur both homogeneously and heterogeneously. The rate coefficient k1 ? 2.1 × 10?24 cm3/molec · sec represents an upper limit (to within a factor of 2 uncertainty) to the direct gas-phase reaction between O3 and H2CO. 相似文献
8.
[structure: see text]. A novel method for the preparation of hydroxy carboxylic acid derivatives has been developed by O2-oxidation of pi-allylnickel intermediates generated by Ni(0)-mediated coupling of 1,2-dienes with CO2. 相似文献
9.
The reaction of OH radicals with CS2 has been investigated by the application of Fourier transform infrared spectroscopy using both photolytic and nonphotolytic competitive techniques in a 420-L reaction chamber at different pressures over the temperature range of 264–293 K. The measured effective rate constant was found to be dependent on total pressure, temperature, and the mole fraction of O2 present in the system. The products of the reaction were found to be COS and SO2 with one molecule of each being formed for every reacted CS2. A value of (2.7 ± 0.6) × 10?12 cm3/molecule·s was obtained as effective rate constant for the reaction at 293 K in 760 torr of synthetic air. 相似文献
10.
CO laser emission at 5 μm was detected when SO2 and CFBr3 were flash photolyzed in the vacuum ultraviolet above 165 nm. Over 40 vibrational–rotational transitions ranging from Δv = 2 → 1 to 14 → 13, with the exception of those between 8 → 7 and 11 → 10, were identified. The CO emission is believed to result from the O + CF reaction: The vibrational population of the CO has been measured by means of a CO laser resonance absorption method. The CO was found to be vibrationally excited to v = 24 with a vibrational temperature of about 1.4 × 104°K. The “surprisal analysis” of the observed CO distribution showed the possible occurrence of a minor process (presumably O + CFBr) that generated vibrationally colder CO. The effects of various additives on the CO emission were also examined. The addition of CO2 to a D2-SO2-CFBr3-He mixture resulted in a simultaneous osciallation at 3.6, 5, and 10.6 μm due to DF, CO, and CO2, respectively. Additionally, the utilization of the O + CFn (n = 1, 2, 3) reactions as F-atom sources for HF-laser operation in flash-initiated systems were demonstrated. 相似文献
11.
Ponciano CR Martinez R Farenzena LS Iza P da Silveira EF Homem MG Naves de Brito A Wien K 《Journal of the American Society for Mass Spectrometry》2006,17(8):1120-1128
Condensed CO and CO2 are bombarded by approximately 65 MeV 252Cf fission fragments and the desorbed ions are analyzed by time-of-flight mass spectrometry as a function of target temperature, in the ranges 25-33 K and 75-91 K, respectively. Absolute desorption yields are measured up to complete ice sublimation. The mass spectra of both ice targets reveal the emission of: (1) low mass ions, produced by direct Coulomb interaction of the highly charged projectiles and delta-electrons with CO and CO2, and (2) pronounced series of cluster ions. The basic ice cluster structures (CO)n and (CO2)n are present in the emitted cluster series such as (CO)nCO+, (CO2)nCO2+, or (CO2)nCO3-. In the case of CO ice, however, the intense production of the series Cn+, Cn-, and (CO)mCn+ shows that Cn is the main cluster structure, consequence of a higher concentration of free carbon atoms in the nuclear track plasma of CO ice than in that of CO2 ice. Ion cluster abundance is observed to decrease exponentially with cluster mass. The decay constant is k(n) congruent with 0.13, about the same for series based on (CO)n and (CO2)n, but a factor 3.3 higher for the Cn series. The Cn clusters are formed by gas-phase condensation, but the (CO)n and (CO2)n clusters are produced by fracturing of the highly excited solid around the nuclear track. A dramatic reduction of the ion desorption yield is observed near T = 29 K for CO and near T = 85 K for CO2, when fast sublimation occurs and ice thickness vanishes. Close to sublimation temperature, the decay constant of the (CO)2Cn+ series increases due to a decreasing formation probability of large Cn clusters. 相似文献
12.
NO2 was photolyzed with 2288 Å radiation at 300° and 423°K in the presence of H2O, CO, and in some cases excess He. The photolysis produces O(1D) atoms which react with H2O to give HO radicals or are deactivated by CO to O(3P) atoms The ratio k5/k3 is temperature dependent, being 0.33 at 300°K and 0.60 at 423°K. From these two points, the Arrhenius expression is estimated to be k5/k3 = 2.6 exp(?1200/RT) where R is in cal/mole – °K. The OH radical is either removed by NO2 or reacts with CO The ratio k2/kα is 0.019 at 300°K and 0.027 at 423°K, and the ratio k2/k0 is 1.65 × 10?5M at 300°K and 2.84 × 10?5M at 423°K, with H2O as the chaperone gas, where kα = k1 in the high-pressure limit and k0[M] = k1 in the low-pressure limit. When combined with the value of k2 = 4.2 × 108 exp(?1100/RT) M?1sec?1, kα = 6.3 × 109 exp (?340/RT)M?1sec?1 and k0 = 4.0 × 1012M?2sec?1, independent of temperature for H2O as the chaperone gas. He is about 1/8 as efficient as H2O. 相似文献
13.
The CS2O+ ion and CS2O molecule were prepared and structurally characterized by mass spectrometric techniques as isolated species in the gas phase. The theoretical analysis, performed by B3LYP and CCSD(T) computational methods, predicted different CS2O+ isomers, SSCO+, O(CS2)+, SCSO+, SCOS+ and S(COS)+, and structurally related singlet and triplet CS2O. Experiment and theory agree in identifying the obtained CS2O+ ions as a mixture of SCSO+ and SCOS+ isomers. CS2O neutral species, prepared by neutralization-reionization mass spectrometry, were directly characterized as intact, long-lived species with a lifetime tau > or =2 micros. 相似文献
14.
15.
16.
《Chemical physics》1986,105(3):449-469
Experimental investigations of mixtures containing predominantly N2O and small amounts of SF6 demonstrate that rapid interspecies pooling of vibrational energy can occur to produce a pulse of excess vibrational energy in the ν3 mode of N2O following excitation of SF6 by a Q-switch CO2 laser. This increased population in the ν3 mode of N2O can occur on a time scale shorter than that on which collision-induced VV processes redistribute vibrational energy among the modes of SF6. The equilibration takes place in three discernible stages: (1) a rapid pooling of energy between a limited number of levels of the SF6 and N2O, then (2) a slower collision-dependent VV process that equilibrates all the vibrational modes in the system, with (3) a subsequent VT,R process that returns the system to its initial state. Argon is shown to accelerate selectively process (2) with an efficiency consistent with the previously measured ability of argon to accelerate the VV process in pure SF6. The experimental evidence indicates that other modes in N2O do not become involved on the time scale on which direct crossing to ν3 occurs. Additionally, on the time scale preceding the SF6 VV equilibration, a fast collision-dependent process competes with the transfer of excitation to N2O. The production of a pulse of excitation in N2O is eliminated when isotopically substituted N2O (14N15NO) is used instead under the same conditions because the crossing rate to the ν3 mode of N2O is decreased sufficiently when 15N is substituted for 14N that it no longer can compete with the VV equilibration among the modes in SF6. 相似文献
17.
18.
19.
《Chemical physics letters》1986,129(4):342-345
A novel emission spectrum extending from 5500 to 8600 Å has been observed during the gas-phase reaction of F2 with CS2. Long progressions in the lower-state (presumably the ground-state) bending frequency and shorter progressions in a ground-state stretching frequency were observed. A partial vibrational analysis is reported, from which two new frequencies are obtained: v″2 = 356 ± 5 and v″3 = 8 31 ± 8 cm−1 .The electronic origin lies near 18500 ± 1200 cm−1. The spectrum is tentatively assigned to the FCS radical. 相似文献