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51.
For any particular fluid, the set of three critical constants (CC) – pressure Pc, temperature Tc and molar volume Vc – has a central importance in defining the physical behaviour of the fluid in the gas and liquid states. However, little attention seems to have been paid in the past to the relations between the CC of different substances. In the present paper, some simple and apparently novel relations have been found between the three CC for the set of four noble gases: Ne, Ar, Kr, Xe. Defining the critical quotient Qc ≡ RTc/Pc (where R is the Gas Constant) the correlations may be summarised by the dual equation: (Vc/cm3 mol−1) = 27 + 0.31 (Tc/K) = 3.3 + 0.280 (Qc/cm3 mol−1), which describes the CC data for the quartet Ne–Xe with an average uncertainty of 0.5%. Regarding the other two noble gases, the two isotopes of the lightest member, 3He and 4He, show the deviations from these relations that are expected from quantal effects and their low molar masses; while for the heaviest member, Rn, the correlations enable a value of 145(5) cm3 mol−1 to be estimated for Vc that is not otherwise well defined in the literature. By contrast, and contrary to the general assumption, the second lightest member, Ne, apparently does not show appreciable quantal effects in the area, so that Ne–Xe may be considered together as a group. These correlations are compared with the behaviour of a selection of polyatomic fluids; in these comparisons, the NG dual correlation equation provides a reference line defining the presumed simplest behaviour. This and related areas show a “Residual Volume Effect”, in that extrapolating the equivalent temperature and energy parameters to zero for the state of zero-mass point particles, referred to here as the hypothetical element zeronium (Ze), the system in each case still has a finite intercept; this intercept amounts to essentially 34% of the average volume for the present quartet Ne–Xe, rather than the zero volume expected for this condition. 相似文献
52.
Dr. Bodo Hattendorf Bianca Gusmini Dr. Ladina Dorta Prof. Dr. Robert S. Houk Prof. Dr. Detlef Günther 《Chemphyschem》2016,17(17):2640-2644
Doubly charged diatomic ions MAr2+ where M=Mg, Ca, Sr or Ba have been observed by mass spectrometry with an inductively coupled plasma ion source. Abundance ratios are quite high, 0.1 % for MgAr2+, 0.4 % for CaAr2+, 0.2 % for SrAr2+ and 0.1 % for BaAr2+ relative to the corresponding doubly charged atomic ions M2+. It is assumed that these molecular ions are formed through reactions of the doubly charged metal ions with neutral argon atoms within the ion source. Bond dissociation energies (D0) were calculated and agree well with previously published values. The abundance ratios MAr+/M+ and MAr2+/M2+ generally follow the predicted bond dissociation energies with the exception of MgAr2+. Mg2+ should form the strongest bond with Ar [D0 (MgAr2+)=124 to 130 kJ mol?1] but its relative abundance is similar to that of the weakest bound BaAr2+ (D0=34 to 42 kJ mol?1). The relative abundances of the various MAr2+ ions are higher than those expected from an argon plasma at T=6000 K, indicating that collisions during ion extraction reduce the abundance of the MAr2+ ions relative to the composition in the source. The corresponding singly charged MAr+ ions are also observed but occur at about three orders of magnitude lower intensity than MAr2+. 相似文献
53.
Dr. Ines E. Collings Dr. Elena Bykova Dr. Maxim Bykov Dr. Sylvain Petitgirard Dr. Michael Hanfland Dr. Damian Paliwoda Prof. Leonid Dubrovinsky Prof. Natalia Dubrovinskaia 《Chemphyschem》2016,17(21):3369-3372
The incorporation of noble gas atoms, in particular neon, into the pores of network structures is very challenging due to the weak interactions they experience with the network solid. Using high‐pressure single‐crystal X‐ray diffraction, we demonstrate that neon atoms enter into the extended network of ammonium metal formates, thus forming compounds Nex[NH4][M(HCOO)3]. This phenomenon modifies the compressional and structural behaviours of the ammonium metal formates under pressure. The neon atoms can be clearly localised within the centre of [M(HCOO)3]5 cages and the total saturation of this site is achieved after ~1.5 GPa. We find that by using argon as the pressure‐transmitting medium, the inclusion inside [NH4][M(HCOO)3] is inhibited due to the larger size of the argon. This study illustrates the size selectivity of [NH4][M(HCOO)3] compounds between neon and argon insertion under pressure, and the effect of inclusion on the high‐pressure behaviour of neon‐bearing ammonium metal formates. 相似文献
54.
Bernard Lavielle Bertrand Thomas Eric Gilabert Gregory Canchel Denis Horlait Sylvain Topin Fabien Pointurier Christophe Moulin 《Journal of mass spectrometry : JMS》2016,51(10):908-913
A double focusing sector field mass filter used in Nier–Johnson geometry has been built in order to perform Kr isotope enrichment for 81Kr and 85Kr isotopes. The principle consists in implanting Kr+ ions accelerated at 7 keV in Al foils after separation using the magnetic sector. A specific ion source has been designed capable of generating high Kr+ ion beams (>0.5 μA) to transfer into the collecting Al foils in 3 to 5 h significant fractions of large Kr samples (1015 to 1016 atoms) initially introduced in the instrument. Implanted Kr isotopes can be further selectively released from the Al foil by surface ablation using an infrared laser beam. Implantation yields and enrichment factors are measured using a conventional mass spectrometer. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
55.
The head-on collision of normal shock waves in dusty gases has been investigated numerically, using the modified random-choice method. The results concerning the various flow field properties as well as the waves configuration were compared with those of a pure gas case. 相似文献
56.
该设计解决了低温工程与低温技术等领域所使用的高纯度气体介质换热的要求,具有显著的经济效益和社会效益。其换热器是由四个管壳式热交换器串联组合而成,壳体呈窄矩形,换热管采用U形换热管,四个管壳式热交换器呈方阵置放在低温换热器筒体内。低温换热器采用的材料是0Cr18N i9/304,该种材料的透气性小、耐磨损、抗腐蚀能力强和性能稳定,防止了气体被污染。另外在低温下,考虑了材料的热胀冷缩所产生的应力,使应力能够自行消除,提高了它的密封性能,最终使低温换热器密封性能好,防止了气体被污染,保证了气体的高纯度。 相似文献
57.
58.
Josephson oscillation of a superfluid Fermi gas 总被引:1,自引:0,他引:1
S. K. Adhikari 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(3):413-419
Using the complete numerical solution of a time-dependent
three-dimensional mean-field model we
study the Josephson oscillation of a superfluid Fermi gas (SFG) at zero temperature formed in a combined axially-symmetric
harmonic plus one-dimensional periodic optical-lattice (OL) potentials after displacing the harmonic trap along the axial
OL
axis. We study the dependence of Josephson frequency on the strength of the OL potential. The Josephson frequency decreases
with increasing strength as found in the experiment of Cataliotti et al. [Science 293, 843 (2001)] for a Bose-Einstein condensate and of the experiment of Pezzè et al. [Phys. Rev. Lett. 93, 120401 (2004)] for an ideal Fermi gas. We demonstrate a
breakdown of Josephson oscillation in the SFG for a large displacement
of the harmonic trap. These features of Josephson oscillation of a SFG can be tested experimentally. 相似文献
59.
D. Lee 《The European Physical Journal A - Hadrons and Nuclei》2008,35(2):171-187
The symmetric heavy-light ansatz is a method for finding the ground state of any dilute unpolarized system of attractive two-component
fermions. Operationally it can be viewed as a generalization of the Kohn-Sham equations in density functional theory applied
to N -body density correlations. While the original Hamiltonian has an exact Z2 symmetry, the heavy-light ansatz breaks this symmetry by skewing the mass ratio of the two components. In the limit where
one component is infinitely heavy, the many-body problem can be solved in terms of single-particle orbitals. The original
Z2 symmetry is recovered by enforcing Z2 symmetry as a constraint on N -body density correlations for the two components. For the 1D, 2D, and 3D attractive Hubbard models the method is in very
good agreement with exact Lanczos calculations for few-body systems at arbitrary coupling. For the 3D attractive Hubbard model
there is very good agreement with lattice Monte Carlo results for many-body systems in the limit of infinite scattering length. 相似文献
60.
J.V. Jovanović S.B. Vrhovac Z.Lj. Petrović 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(3):335-342
Transport properties of ion swarms in presence of Resonant Charge Transfer (RCT) collisions are studied using Momentum Transfer
Theory (MTT). It was shown that, not surprisingly, RCT collisions may be represented as a special case of elastic scattering.
Using the developed MTT we tested a previously available anisotropic set of cross-sections for Ar+Ar
+ collisions by making the comparisons with the available data for the transverse diffusion coefficient. We also developed
an anisotropic set of Ne+Ne
+ integral cross-sections based on the available data for mobility, longitudinal and transverse diffusion. Anisotropic sets
of cross-sections are needed for Monte Carlo simulations of ion transport and plasma models.
Received 16 June 2002 / Received in final form 2nd August 2002 Published online 24 September 2002
RID="a"
ID="a"e-mail: vrhovac@phy.bg.ac.yu
RID="b"
ID="b"e-mail: zoran@phy.bg.ac.yu 相似文献