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Infrared spectrum of the cobalt carbonyl radical CoCO produced by the 193 nm excimer laser photolysis of cobalt tricarbonyl nitrosyl Co(CO)3NO was observed by time-resolved diode laser spectroscopy. More than 600 lines were identified as belonging to the ν1 (C-O stretch) fundamental band, consisting of the Ω=5/2 and 3/2 subbands, and the associated hot bands , , , and . The 2Δi electronic ground state of CoCO was experimentally confirmed. The ν1 band origins are 1974.172582(93) cm−1 and 1973.53178(14) cm−1 for the Ω=5/2 and 3/2 subbands, respectively. The rotational constant in the ground state was determined as B0=4427.146(50) MHz. The centrifugal distortion constant D0=1.1243(68) kHz was obtained for the Ω=5/2 substate of the ground state. The equilibrium rotational constant Be=4435.44(14) MHz was derived, together with the vibration-rotation interaction constants.  相似文献   

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Magnetic susceptibility obtained from magnetization measurement (for fields H=0.1 and 1.0 T) of polycrystalline Eu2Ti2O7 shows two distinct features. Firstly, increases on cooling below 300 K and attains a temperature-independent constant value at 68 K (Tmax). Secondly, shows an antiferromagnetic increase below 4.9±0.1 K. The former behavior is explained by crystal field (CF) theory. CF levels and wave functions of ground and excited states are determined accurately from analyses of and earlier reported Mössbauer and optical spectra. Analysis of vs. 1/T curve at low temperatures gives the classical nearest-neighbor exchange interaction Jcl=−0.76 K and a weak dipolar interaction Dnn=0.0056 K. CP of polycrystalline sample of Eu2Ti2O7 and Y2Ti2O7 are measured between 1.8-35 and 1.8-120 K respectively and θD vs. T (K) curves are calculated. At 4 K, θD of Eu2Ti2O7 shows a kink and dCP/dT curve show a maximum. Optical results show energy exchange between Eu3+ ions at intrinsic and extrinsic (defect) sites via super-exchange interaction at low temperature which may account for the observed anomalous behavior of and CP.  相似文献   

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Using multireference configuration-interaction methods and double to triple-zeta basis sets with semidiffuse and polarization functions, potential energies and spectroscopic constants for low-lying doublet, and quartet states of AlN were calculated. has Re=3.280 bohr and . lies 0.17 eV above the ground state. Using an estimated electron affinity of 2.1 eV for AlN, four states of AlN are found to be stable, namely , , , and . Comparisons with the isovalent anions BN (three stable states) and AlP (seven stable states) are made. Photo-detachment of an electron from the state of AlN can lead to an accurate determination of the energy difference between the two close-lying lowest states of AlN, and , predicted here to be 0.09 eV apart.  相似文献   

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We investigate the dynamics of a macroscopic system which consists of an anharmonic subsystem embedded in an arbitrary harmonic lattice, including quenched disorder. The coupling between both parts is bilinear. Elimination of the harmonic degrees of freedom leads to a nonlinear Langevin equation with memory kernels and noise term for the anharmonic coordinates . For zero temperature, i.e. for , we prove that the support of the Fourier transform of and of the time averaged velocity-velocity correlation functions of the anharmonic system cannot overlap. As a consequence, the asymptotic solutions can be constant, periodic, quasiperiodic or almost periodic, and possibly weakly chaotic. For a sinusoidal trajectory with frequency we find that the energy ET transferred to the harmonic system up to time T is proportional to Tα. If equals one of the phonon frequencies ων, it is α=2. We prove that there is a zero measure set L such that for in its full measure complement R?L, it is α=0, i.e. there is no energy dissipation. Under certain conditions L contains a subset L such that for the dissipation rate is nonzero and may be subdissipative (0≤α<1) or superdissipative (1<α≤2), compared to ordinary dissipation (α=1). Consequently, the harmonic bath does act as an anomalous thermostat, in variance with the common belief that elimination of a macroscopically large number of degrees of freedom always generates dissipation, forcing convergence to equilibrium. Intraband discrete breathers are such solutions which do not relax. We prove for arbitrary anharmonicity and small but finite coupling that intraband discrete breathers with frequency exist for all in a Cantor set C(k) of finite Lebesgue measure. This is achieved by estimating the contribution of small denominators appearing for , related to . For the small denominators do not lead to divergencies such that is a smooth and bounded function in t.  相似文献   

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The rotational spectrum of the iron monosulfide radical, FeS, was measured in the frequency region of 220-390 GHz with a source-modulated millimeter/submillimeter-wave spectrometer. The radical was efficiently produced in a free space absorption cell by a dc discharge in a mixture of Ar and H2S with a stainless-steel hollow cathode. Several series of paramagnetic lines were detected with intervals of about 12 GHz. The four series having relatively strong intensity were assigned to FeS in the vibrationally ground state of the X5Δi electronic state, two series to that in the vibrationally excited state, and five series presumably to FeS in the electronically excited state, . The effective molecular constants were determined for FeS in the X5Δi electronic state. The components of the vibrationally ground state showed an apparent shift from the typical pattern of the state. In addition, the fine structure of the state was found to be far from a regular pattern expected for a state. A trial analysis including electronic interaction between the and states was carried out, but it was not possible to explain the spectral lines of both electronic states simultaneously. Reasons for the heavily perturbed spectral patterns are discussed.  相似文献   

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In a recent theoretical paper, vibrational frequencies were reported for CBrCl in the and à states. These values agree well with our previously published experimental frequencies, except in the case of , where the theoretical value of 968.3 cm−1 is significantly higher than the experimental value of 712.6 cm−1. This discrepancy prompted a re-examination of the assignments for transitions involving ν1 in the laser induced fluorescence spectrum. If the progression ν1 + 2 has the assignment of n reduced by 1 (the origin is not observed), a new experimental value of results. The close accord with the theoretical value lends weight to this re-assignment. Consequently we propose that the experimental frequency be changed to .  相似文献   

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Miriam Lemanska 《Physica A》2008,387(12):2719-2735
A dynamical system of infinite volume and of infinite number of identical interacting particles occupying energy levels has been constructed as the limit of an infinite sequence of finite, equivalent systems of increasing size and particle number. Systems both in equilibrium and in non-equilibrium state (designated S=limSk, , respectively, k=1,2,…) were investigated. The main results are:(i) The values in the T-limit (thermodynamic limit) of the physical quantities characterizing these systems are determined.(ii) The time evolution process both in and in systems is governed by the non-linear rate equations with common initial conditions pi(t0), where pi(t)=ni(t)/N are the occupation probabilities at time t. The time evolution process in the and systems is the same. The asymptotic approach to the equilibrium state is proved.(iii) For the case of the equilibrium state, the Boltzmann probability distribution pi is given by the equation −lnpi+a+eib=0 common to Sk and S systems with the same value of a and b. The term a=β−1ae, where ae is the free energy per particle, and .(iv) The conditions for the equivalence of the systems being in equilibrium and also of the ones in non-equilibrium are stated.  相似文献   

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Magnetic susceptibility of powder Er2Ti2O7 (ErT) is measured between 300 K and 80 K. shows a Curie-Weiss (CW) type behaviour with   ErTiO3.5 and . A crystal field (CF) analysis of our experimental data, g-values (g=0.27 and g=7.8) and the positions of two CF levels (reported earlier from an inelastic neutron scattering study) provide CF parameters and CF levels of the ground 4I15/2 and excited multiplets of ErT. The theoretical follows a CW-type behaviour, with . Single-ion magnetic anisotropy (χχ) is 9500×10−6 emu/mol ErTiO3.5 at 300 K, which increases by ∼54 times at 10 K and ErT resembles an XY planar system. It can be inferred from CF analysis that the earlier observed change of from −13 K to −22 K below 50 K is not due to the CF effect. Nuclear hyperfine (HF) levels of 167ErT and 166ErT are calculated and the theoretical curve of vs. T (K) for T<TN matches the observed results. Mössbauer lines expected for 166ErT are also predicted.  相似文献   

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Low temperature magnetic (M) and thermal (CP) properties of the intermetallic compound Ce2Pd2Sn have been investigated at zero and different magnetic fields. Two transitions were recognized at and , with latter nearly coinciding with the extrapolated Curie-Weiss temperature . The Curie factor evaluated from TTM, is ≈2μB. The positive value of θP, the triangular coordination of the magnetic (Ce) atoms and the weak effect of applied magnetic field, reveal that TM cannot be considered as a canonic antiferromagnetic transition like claimed in the literature. M(T) measurements under moderate magnetic fields () show TC(B) increasing while TM(B) is practically not affected. Both transition merge in a critical point at for , where the intermediate phase is suppressed. At , the cusp of a first order transition is observed in CP(T). According to the proposed ferromagnetic ground state, it is followed by a CP(T)∝T3/2exp(-Eg/T) dependence, with a gap of anisotropy .  相似文献   

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Rotationally resolved ultrahigh-resolution fluorescence excitation spectra of the S1 ← S0 transition of dibenzofuran have been observed using the technique of crossing a collimated molecular beam and the single-mode UV laser beam. 3291 rotational lines of the band and 3047 rotational lines of the band have been assigned. The band has been found to be a b-type transition, in which the transition moment is along the twofold symmetry axis of this molecule, and only the ΔKa = ± 1 transitions were observed. The excited state is identified to be the S11A1(ππ) state. In contrast with this, the band has been found to be an a-type transition in which the transition moment is along the long axis in plane. It indicates that the intensity of this vibronic band arises from vibronic coupling with the S21B2(ππ) state. We determined the accurate rotational constants and the molecule have been shown to be planar both in the ground and excited states.  相似文献   

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