共查询到20条相似文献,搜索用时 15 毫秒
1.
Ch. Hertzler W. F. Staudt H. -J. Foth 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1992,23(2):99-100
The accuracy for the direct measurement of the dissociation energy of the N 2 + B2Σ u +-state was significantly improved by using frequency doubled laser light, which enables the authors to excite from lowerv″-levels and additionally to calibrate the fundamental laser wavelength with an iodine cell. The obtained value is:D 8(N 2 + )=70248±6 cm?1. 相似文献
2.
Franck–Condon factors are presented for the normal and stable isotope-labelled N2, O2, NO and CO molecules for transitions to the observed ionized states by using the Rydberg–Klein–Rees (RKR ) potential energy curves of the various electronic states involved. It has been observed that for some transitions, the Franck–Condon factors based on the RKR potential energy curves differ appreciably from those based on the Morse potential function. The effect of isotopic substitution on the transition probabilities is also quite significant in a number of cases. 相似文献
3.
An apparatus containing cross molecular and pulsed electron beams has been used to obtain distributions in kinetic energy and angle of fast (? 0.5 eV) positive ions produced through dissociative ionization of N2 and O2 by impact of 50 to 2000 eV electrons. Four main O+ ion groups are observed with peak energies of 0.8, 2.0, 3.0, and 5.0 eV. Two main N+ groups peaking at 2.0 and 3.0 eV are seen. Angular distributions of both N+ and O+ ions are essentially isotropic for electron-beam-ion detection angles from 30° to 110°. 相似文献
4.
Quasiclassical trajectory calculations are reported to investigate the effects of rotational excitation of formaldehyde on the branching ratios of the fragmentation products, H2+CO and H+HCO. The results of tens of thousands of trajectories show that increased rotational excitation causes suppression of the radical channel and enhancement of the molecular channel. Decomposing the molecular channel into "direct" and "roaming" channels shows that increased rotation switches from suppressing to enhancing the roaming products across our chosen energy range. However, decomposition into these pathways is difficult because the difference between them does not appear to have a distinct boundary. A vector correlation investigation of the CO rotation shows different characteristics in the roaming versus direct channels and this difference is a potentially useful signature of the roaming mechanism, as first speculated by Kable and Houston in their experimental study of photodissociation of acetaldehyde [P. L. Houston and S. H. Kable, Proc. Nat. Acad. Sci. 103, 16079 (2006)]. 相似文献
5.
Yatsuhisa Nagano Yuhji Achiba Kenji Sato Katsumi Kimura 《Chemical physics letters》1982,93(5):510-514
Kenetic energies and angular distributions of photoelectrons emitted by three-photon ionization fo atomic iron through two-photon resonant state e7DJ and e5 DJ, were measured, by using visible lasers. J-resolved photoelectron bands attributab to the a6DJ and a4Fj ionic states are reported. 相似文献
6.
C. H. Becker 《Fresenius' Journal of Analytical Chemistry》1991,341(1-2):3-6
Summary A general surface analysis method has been developed based on non-selective photoionization of sputtered or desorbed neutral atoms and molecules above the surface, followed by time-of-flight mass spectrometry. The approach, currently utilizes two main types of ionizing radiation and a variety of desorption probes. For photoionization, coherent untuned sources are used; an intense focused pulsed UV laser beam is used for non-resonant multiphoton ionization to give elemental and limited chemical information, usually used for inorganic analysis; a coherent VUV source is used for single-photon ionization at 118 nm (10.5 eV) produced by frequency tripling of 355 nm light from a Nd:YAG laser. This paper focuses on single-photon ionization for inorganic systems. The desorption probes used are ion, electron, and laser beams as well as thermal desorption. For depth profiling, ion beams are specifically used. Any focused desorption probe beam can provide lateral spatial resolution. 相似文献
7.
Arne Stindt Merwe Albrecht Ulrich Panne Jens Riedel 《Analytical and bioanalytical chemistry》2013,405(22):7005-7010
For many analytical purposes, direct laser ionization of liquids is desirable. Several studies on supported droplets, free liquid jets, and ballistically dispensed microdroplets have been conducted, yet detailed knowledge of the underlying mechanistics in ion formation is still missing. This contribution introduces a simple combination of IR-MALDI mass spectrometry and an acoustical levitation device for contactless confinement of the liquid sample. The homebuilt ultrasonic levitator supports droplets of several millimeters in diameter. These droplets are vaporized by a carbon dioxide laser in the vicinity of the atmospheric pressure interface of a time of flight mass spectrometer. The evaporation process is studied by high repetition rate shadowgraphy experiments elucidating the ballistic evaporation of the sample and revealing strong confinement of the vapor by the ultrasonic field of the trap. Finally, typical mass spectra for pure glycerol/water matrix and lysine as an analyte are presented with and without the addition of trifluoracetic acid, and the ionization mechanism is briefly discussed. The technique is a promising candidate for a reproducible mass spectrometric detection scheme for the field of microfluidics. Figure
CO2 laser evaporation of an acoustic levitated droplet followed by time of flight mass analysis 相似文献
8.
The angular distribution of products from the ultraviolet photodissociation of nitrous oxide yielding O((1)D) and N(2)(X Σ(g)(+)(1)) was investigated using classical trajectory calculations. The calculations modeled absorption only to the 2(1)A(') electronic state but used surface-hopping techniques to model nonadiabatic transitions to the ground electronic state late in the dissociation. Observed values of the anisotropy parameter β, which decrease as the product N(2) rotational quantum number j increases, could be well reproduced. The relatively low observed β values arise principally from nonaxial recoil due to the very strong bending forces present in the excited state. In the main part of the product rotational distribution near 203 nm, an unusual dynamical effect produces the decrease in β with increasing j; nonaxial recoil effects remain approximately constant while higher j product molecules arise from parent molecules that had their transition dipole moments aligned more closely along the molecular axis. In both low and high j tails of the rotational distribution, the variations in β with j are caused by changes in the extent of nonaxial recoil. In the high-j tail, additional torque present on the ground state potential energy surface following nonadiabatic transitions causes both the additional rotational excitation and the lower β values. 相似文献
9.
CO2加氢直接制取二甲醚的研究 总被引:29,自引:1,他引:29
CO2加氢直接制取二甲醚的研究葛庆杰黄友梅1)邱凤炎李树本(中国科学院兰州化学物理研究所兰州730000)关键词二氧化碳催化加氢二甲醚铜催化剂分类号O643.32二氧化碳在地球上含量极丰富,且随着工业的发展而日益增长.同时二氧化碳含量的日益增多,会加... 相似文献
10.
The synthesis of angularly fused quinone natural products has been achieved using a photoenolization reaction and a Diels-Alder reaction in the key carbon-carbon bond forming steps. 相似文献
11.
H. Geisen D. Neuschäfer Ch. Ottinger 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1990,17(2):137-144
From very high resolution (8 MHz FWHM) LIF measurements, the hyperfine coupling constants of N2(A 3Σ u + ) and N2(B 3Π g ) have been obtained for three pairs of vibrational quantum numbersv′,v″. TheA-state constants are in very good agreement with accurate literature data. The vibrational dependence of some of theB-state constants is found to be much more pronounced. This is qualitatively explained in terms of the electronic structure of the two states. 相似文献
12.
Molecular beam scattering dynamics at the gas-liquid interface are investigated for CO2 (E(inc) = 10.6(8) kcal/mol) impinging on liquid perfluoropolyether (PFPE), with quantum state (v, J) populations measured as a function of incident (theta(inc)) and final (theta(scat)) scattering angles. The internal state distributions are well-characterized for both normal and grazing incident angles by a two-component Boltzmann model for trapping desorption (TD) and impulsive scattering (IS) at rotational temperatures T(rot)(TD/IS), where the fractional TD probability for CO2 on the perfluorinated surface is denoted by TD and IS densities (rho) as alpha = rhoTD/(rhoTD + rhoIS). On the basis of an assumed cos(theta(scat)) scattering behavior for the TD flux component, the angular dependence of the IS flux at normal incidence (theta(inc) = 0 degrees) is surprisingly well-modeled by a simple cos(n)(theta(scat)) distribution with n = 1.0 +/- 0.2, while glancing incident angles (theta(inc) = 30 degrees, 45 degrees, and 60 degrees) result in lobular angular IS distributions scattered preferentially in the forward direction. This trend is also corroborated in the TD fraction alpha, which decreases rapidly under non-normal incident conditions as a function of backward versus forward scattering direction. Furthermore, the extent of rotational excitation in the IS channel increases dramatically with increasing angle of incidence, consistent with an increasing rotational torque due to surface roughness at the gas-liquid interface. 相似文献
13.
14.
Eland JH Andric L Linusson P Hedin L Plogmaker S Palaudoux J Penent F Lablanquie P Feifel R 《The Journal of chemical physics》2011,135(13):134309
Spectra of triply ionized CO(2) have been obtained from photoionization of the molecule using soft x-ray synchrotron light and an efficient multi-electron coincidence technique. Although all states of the CO(2) (+++) trication are unstable, the ionization energy for formation of molecular ions at a geometry similar to that of the neutral molecule is determined as 74 ± 0.5 eV. 相似文献
15.
Anab initio study of the electronic structure of several 22-electrons molecules is presented. The equilibrium geometries of their ground state are calculated at the SCF level using the 6–31G basis set and are found to be in good agreement with the experimental geometries. The dissociation process of these molecules leading to the isoelectronic products CO or N2 on the one hand and BH3, CH2, NH and O on the other hand is studied. The least-energy dissociation paths of the ground states determined at the SCF level are compared on the basis of electron density interactions. The dissociation energies corresponding to the two lowest dissociation channels are calculated. In these calculations, the correlation energy is taken into account using a non-variational method developed previously. The calculated values of dissociation energies are in good agreement with the existing experimental values. The results permit to predict values for HNCO, BH3CO and CH2N2 and to confirm the instability of BH3N2.Aspirant du Fonds National Belge de la Recherche Scientifique. 相似文献
16.
Santana-Solano J Wu DT Marr DW 《Langmuir : the ACS journal of surfaces and colloids》2006,22(13):5932-5936
We have measured the influence of both applied alternating current (AC) field strength and frequency on the electrohydrodynamic (EH) flows present in colloidal systems near an electrode surface. The effect of the flows is visualized by the rotation of the colloids, fluorescently labeled by a novel technique involving EH-driven aggregation of much smaller tracer colloids to the surface of the larger colloids. Our results show an E2 dependence of these flows, consistent with an induced charge mechanism for effective colloidal interactions. We have also observed a crossover in frequency that suggests a change in the origin of the induced charge, consistent with predictions from available theory. The EH flows appear to be hydrodynamically screened inside clusters, as evidenced by the lack of rotation of interior colloids and the cluster-size independent rotation rate of colloids on the boundary. 相似文献
17.
The linear correlation between the term value and ionization energy for molecular Rydberg transitions is tested for the sequence of isoelectronic molecules BF, CO and N2 based on a new measurement of the absorption spectrum of CO and data for BF and N2. For the npσ series and npπ series converging on the first ionization potential, we find an excellent linear behavior (within 10 meV) corroborating (i) the correlation and (ii) the individual assignments. For Rydberg series leading to the A 2Π and B 2Σ+ states, where no data for BF are available, a comparison of term values for CO and N2 is presented. 相似文献
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19.
Sizova A. A. Grintsevich S. A. Kochurin M. A. Sizov V. V. Brodskaya E. N. 《Colloid Journal》2021,83(3):372-378
Colloid Journal - Grand canonical Monte Carlo simulations were performed to study the occupancy of structure I multicomponent gas hydrates by CO2/CH4, CO2/N2, and N2/CH4 binary gas mixtures with... 相似文献
20.
The rate coefficient for the reaction of the peroxypropionyl radical (C2H5C(O)O2) with NO was measured with a laminar flow reactor over the temperature range 226–406 K. The C2H5C(O)O2 reactant was monitored with chemical ionization mass spectrometry. The measured rate coefficients are k(T) = (6.7 ± 1.7) × 10−12 exp{(340 ± 80)/T} cm3 molecule−1 s−1 and k(298 K) = (2.1 ± 0.2) × 10−11 cm3 molecule−1 s−1. Our results are comparable to recommended rate coefficients for the analogous CH3C(O)O2 + NO reaction. Heterogeneous effects, pressure dependence, and concentration gradients inside the flow reactor are examined. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet: 31: 221–228, 1999 相似文献