Selective effects of homogeneous and heterogeneous reactions in the system N21-CO

In the system N₂¹-CO, effects arising only from the reactions in the homogeneous phase have been isolated in a reactor with inert walls. After an induction period of 0.13 s, they involve a stationary rate of enhancement of N₂(B³Π_g) and N(⁴S) concentrations according to the reactions N₂(X¹Σ_g⁺)_v¹+CO→ CO(X¹Σ⁺)_v1 + N₂(X¹Σ_g⁺ and CO(X¹Σ⁺)_v1 + N₂(A³Σ_u⁺) → N (⁴S) + N(⁴S) + CO(X¹Σ⁺).In a reactor with active walls, both the above reactions in the homogeneous phase and heterogeneous reactions due to CO adsorbed on the walls are involved according to CO_ads + N₂(X¹Σ_g⁺)_{v1 ads or not} → CO(X¹Σ⁺)_v1 + N₂(X¹Σ_g⁺ and N(⁴S) + N(⁴S) + CO_ads → N₂(X¹Σ_g⁺) + CO(X¹Σ⁺)N(⁴S) + CO_ads → N₂(X¹Σ_g⁺) + CO(X¹Σ⁺). In this case, the rate of enhancement is not stationary. Furthermore, for cylindrical reactors with large diameters, the two types of reaction do not interact and their effects are additive.     

Comments on the measurements of vibrational intensity in the photoelectron spectra of N2 and CO,for the ionic ground state

Over 50 experimental values of the photoelectron intensity I(v′ = 1) (normalized to I(v′ = 0) equal to 100) for the N₂⁺, X²Σ_g⁺ photoelectron band, as well as 17 values of I(v′ = 1) for CO⁺, X²Σ⁺, are gathered or calculated from literature data, compared and discussed. Differences in the types of analyzer used, the instrumental conditions, the character of the UV light employed and the type of possible intensity corrections make such a comparison difficult, leave unexplained discrepancies and show the necessity of more systematic experimental investigations.     

Photoionization and photoelectron angular distribution for H2

Photoionization of H₂(¹Σ_g⁺) in a vibrational υ″ and rotational N″ state into H₂⁺(²Σ_g⁺) in a vibrational υ′ and rotational N′ state is studied theoretically. The differential cross section, after summing over the final states, is expressed in the well-known simple form of $\text{(}\text{σ}{}_{\mathrm{T}}\text{4π}\text{)[1 + βP}{}_2\text{(}\text{cos}\text{θ)]}$. Parallel expressions are obtained for H₂⁺ in a specific υ′ state (in terms of σ(υ′) and β(υ′)) and for H₂⁺ in a rotational fine level υ′N′ (in terms of σ(υ′N′) and β(υ′N′)). Asymmetry parameters β, β(υ′) and β υ′N′), which are expressed in terms of Racah and Clebsch-Gordan coefficients and electronic transition moments, can be reduced approximately to 2 lineary polarized light and to -1 for unpolarized light. Using single-center electronic wave functions and including partial eaves l = 1, 3, and 5, σ(υ′) and β(υ′) are computed as a function of υ′ at 584 Å. The computed σ(υ′) divided by the Frank-Condon overlap, in agreement with experimental results, increases monotonically with υ′; σ_T and β are computed in the incident photon energy range of 600–4000 Å and the results compare favorably with previous calculations.     

The use of electron impact dissociation and the photon-photon cascade technique to measure the lifetime of the B2Σ+ state of CN

The lifetime of the (B³Σ⁺_{υ= 0, 1} state of the CN radical has been measured by the photon-photon delayed coincidence technique, the CN radical being produced by electron impact dissociation of acetonitrile. This is the first lifetime measurement in a free radical by this method. The optical cascade in the band spectrum of CN used for the present measurement is H²Π_r - B²Σ⁺ - X²Σ⁺. The lifetime of the (B²Σ⁺)_{υ=0, 1} state in CN has been found to be 61.1 ± 7.6 ns.     

C2H221分子转动角动量定向分布(Orientation)及其碰撞弛豫和转移

利用圆偏振激光受激Raman抽运,以 C₂H₂分子为样品选择性地制备了它的电子基态单一转动态(X¹Σ⁺_g,ν″₂＝1,J″的角动量定向布居(orientation)．并从圆偏振紫外激光诱导的A¹A_u(ν′₃＝1)←X¹Σ⁺_g(ν″₂＝1)的荧光（谱）,直接测定了 C₂H₂(X¹Σ^＋_g,ν″₂＝1,J″＝4,7,8,…,13）的角动量定向布居值．从时间分辨的荧光信号谱测定了角动量定向布居的碰撞弛豫速率常数,同时还研究了由各初始激励的转动态向其他邻近转动态碰撞诱导的角动量定向布居转移． 关键词：     

The bΣ(b0) → XΣ(X10,X21) and aΔ(a2) → X21 transitions of AsBr

Emission spectra of the b¹Σ⁺(b0⁺) → X³Σ⁻(X₁0⁺,X₂1) and a¹Δ(a2) → X₂1 transitions of AsBr have been measured in the near-infrared spectral region with a Fourier-transform spectrometer. The arsenic bromide radicals were generated in fast-flow systems by reaction of arsenic vapor (As_x) with bromine and were excited by microwave-discharged oxygen. The most prominent features in the spectrum are the Δv = +1,0,−1, and −2 band sequences of the b¹Σ⁺(b0⁺) → X³Σ⁻(X₁0⁺) transition in the range 11 700-12 700 cm⁻¹. With lower intensities, the Δv = 0 and −1 sequences of the b¹Σ⁺(b0⁺) → X³Σ⁻(X₂1) sub-system show up in the same range. Further to the red, between 6000 and 6700 cm⁻¹, the Δv = 0, +1, and −1 sequences of the hitherto unknown a¹Δ(a2) → X₂1 transition are observed. Analyses of medium- and high-resolution spectra have yielded improved molecular constants for the X₁0⁺, X₂1, and b0⁺ states and first values of the electronic energy and the vibrational constants of the a2 state.     

用MRCI方法研究CS+同位素离子X2Σ+和A2Π态的光谱常数与分子常数

利用内收缩多参考组态相互作用方法和价态范围内的最大相关一致基aug-cc-pV6Z, 在0.05—0.60 nm的核间距范围内计算了CS⁺离子X²Σ+和A²Π态的势能曲线. 利用CS⁺离子的势能曲线并在同位素质量修正的基础上, 拟合出了X²Σ+和A²Π态的同位素离子^{1 关键词： 同位素识别 势能曲线 光谱常数 分子常数}     

The vacuum uv emission spectrum of the 15N22+ molecular ion

The vacuum uv emission of the ¹⁵N₂²⁺ ion has been recorded for the first time. Rotational analysis of two bands, analogous to those already observed in the case of the natural isotope, confirm their assignment to the D¹Σ_u⁺-X¹Σ_g⁺ (0, 0) and (1, 1) bands. More precise data are also obtained for the ³Σ_g^? state which perturbs ground state vibrational levels.     

A global potential energy surface for H2S+(X 4A′′) and quasi-classical trajectory study of the S+(4S) + H2(X1Σ+g) reaction

A novel global potential energy surface for H₂S⁺(X?⁴A″) based on accurate ab initio calculations is presented. Energies are calculated at the multi-reference configuration interaction level with Davidson correction using aug-cc-pVQZ basis set plus core-polarisation high-exponent d functions. A grid of 4552 points is used for the least-square fitting procedure in the frame of a many-body expansion. The topographical features of the new potential energy surface are here discussed in detail. Such a surface is then employed for dynamic studies of the S(⁴S) + H₂(X?¹Σ⁺_g) →SH⁺(X?³Σ^?) + H(²S) reaction using the quasi-classical trajectory method. State specific trajectories are calculated, for both ground and ro-vibrationally excited initial states of H₂(X?¹Σ⁺_g). Corrections to the zero point energy leakage of the classical calculations are also presented. Calculated reaction cross sections and rate constants are here reported and compared with available literature.     

Studies on the Vibrational and Rovibrational Energies and Vibrational Force Constants of Diatomic Molecular States Using Algebraic and Variational Methods

Alternative expressions for vibrational and rotational spectrum constants and energies of diatomic molecular electronic states based on perturbation theory are suggested. An algebraic method (AM) is proposed to generate a converged full vibrational spectrum from limited energy data, and a potential variational method (PVM) is suggested to produce the vibrational force constants f_n and rotational spectrum constants using the perturbation formulae and the AM vibrational constants. The AM and PVM have been applied to study 10 diatomic electronic states: the X¹Σ_g⁺ and C¹Π_u⁻ states of H₂; the X¹Σ_g⁺, A³Σ_u⁺, B′³Σ_u⁻, and B³Π_g states of N₂; the X³Σ_g⁻, A³Σ_u⁺, and c¹Σ_u⁻ states of O₂; and the X¹Σ_g⁺ state of Br₂. Calculations show that (1) the AM E_υmax converges to the correct molecular dissociation energy; (2) the AM not only reproduce the input energies, but also generate the E_υ's of high vibrational excited states which may be difficult to obtain experimentally or theoretically; (3) the PVM vibrational force constants f_n may be used to measure the relative chemical bondstrengths of different diatomic electronic states for a molecule quantitatively.     

分子部分电子态的高阶振动能级和离解能的精确研究

鉴于K₂分子电子态的振动能谱和分子离解能D_e在实际研究和应用中的重要性,应用Sun,Ren等人提出的基于微扰理论的代数方法(AM)和基于AM的代数能量方法(AEM)研究了K₂分子的X¹Σ⁺_g,a³Σ⁺_u,0^-_g,B¹Π_{u< 关键词： 2}分子')" href="#">K₂分子 代数方法 高阶振动能级 离解能     

The electronic spectrum of AgBr2: Ab initio benchmark vs. DFT calculations on the lowest ligand-field states including spin-orbit effects

The X²Π_g, ²Σ_g⁺ and ²Δ_g states of AgBr₂ have been studied through benchmark ab initio CASSCF + Averaged Coupled Pair Functional (ACPF) and DFT calculations using especially developed valence basis sets to study the transition energies, geometries, vibrational frequencies, Mulliken charges and spin densities. The spin-orbit (SO) effects were included through the effective hamiltonian formalism using the |ΛSΣ〉 ACPF energies as diagonal elements. At the ACPF level, the ground state is ²Π_g, in contradiction with ligand-field theory and Hartree-Fock results. The ACPF adiabatic excitation energies of the ²Σ_g⁺ and ²Δ_g states are 3825 and 20 152 cm⁻¹, respectively. The inclusion of the SO effects leads to a pure Ω = 3/2 (²Π_g) ground state, a Ω = 1/2 (97% ²Π_g + 3% ²Σ_g⁺) A state, a Ω = 1/2 (3% ²Π_g + 97% ²Σ_g⁺) B state, a Ω = 5/2 (²Δ_g) C state and a Ω = 3/2 (99% ²Δ_g) D state. The B97, B3LYP and PBE0 functionals, which were shown to yield accurate transition energies for CuCl₂, overestimate the X²Π_g-²Σ_g⁺ T_e by around 25% but provide a qualitative energetic ordering in agreement with CASSCF and ACPF results. The nature of the bonding in the X²Π_g ground state is different from that of AgCl₂ since the Mulliken charge on the metal is 0.95 while the spin density is only 0.39. DFT strongly delocalizes the spin density providing even smaller values of around 0.13 on Ag not only for the ground state, but also for the ²Σ_g⁺ state.     

Variation of electronic transition moment with the internuclear separation for the (AO+−X1Σ+) band system of PbO

Relative integrated intensities of the (AO⁺?X¹Σ⁺) band system of PbO have been measured by photographic photometry. These have been interpreted with the aid of Franck-Condon factors (q_υ′υ″) and r-centroids ($\text{r}{}_{\mathrm{\upsilon \prime \upsilon ″}}$) to show that the variation of electronic transition moment with internuclear separation is R_e(r)=const.(0.521r?1). Arrays are shown for the band strengths S_υ′υ″.     

Pulsed supersonic source of vdW complexes for high-temperature applications: Spectroscopy and beam characteristics

Application of a modified version of high-temperature high-pressure all-metal pulsed source of supersonic molecular beam is demonstrated in a production of van der Waals (vdW) complexes. The vdW complexes are produced possessing controllable rotational temperature (T _rot ) in the range from 3 K to 19 K. An effective control over T _rot is illustrated employing excitation spectrum recorded using the B ³1(5³ P ₁) ← X ¹0⁺(5¹ S ₀) transition in CdAr. First-time resolved rotational structure in the profile of the υ′ = 2←υ′′ = 0 vibrational component is reported. The control over T _rot is crucial in a dissociation of the (¹¹¹Cd)₂ isotopologue in the supersonic beam. For the process, excitation at well defined J′← J′′ rotational transition within the (υ′,υ′′) = (40,0) vibrational band of the A ¹0 _u ⁺(5¹ P ₁) ← X ¹0 _g ⁺(5¹ S ₀) transition is employed. It is followed by the dissociation using A ¹0 _u ⁺(υ′ = 40,J′′) → X ¹0 _g ⁺ bound → free transition. An analysis and simulation of the (40,0) vibrational band rotational structure are presented. Parameters describing conditions in the supersonic beam, degree of rotational cooling, Doppler broadening and spectral bandwidth of the laser beam are used.     

Relative intensities of the rotational lines of the (0, 0) and (0, 1) bands of the B2Σ+u-X2Σ+g systems of N+2

A high resolution grating spectrometer and a hollow-cathode lamp were used to study the relative intensities for lines of the transition B²Σ⁺_u→X²Σ⁺_g of the ion N⁺₂. Mulliken's formulae are obeyed with a precision of better than 2% for N^′?30, except for the first two lines, for which the relative intensities of the P lines are 2.5% greater than Mulliken's values and the relative intensities of the R lines 2.5% lower. The differences in the positions of the doublets for the first lines increase linearly (γ′?γ″=0.015±0.002cm^-1 with γ″≈0.010cm^-1) for N′?10. An interpretation of this difference gives an order of magnitude for the perturbation parameters of the state A²Π_u(v′=10)(ξ≈9cm^-1, η≈0.06cm^-1). The effect of this perturbation on the line intensities is negligible for N′?30.     

Observation of the c3Πu-X1Σg+ intersystem transition in the absorption spectrum of P2

The observation of the c³Π_u-X¹Σ_g⁺ intersystem transition of P₂ is reported. The 6-0 band of the system was identified on high resolution absorption plates teken on the NRC 10-m vacuum spectrograph at Ottawa. A rotational analysis of the band is given together with that of the adjacent 5-0 band of the C¹Σ_u⁺-X¹Σ_g⁺ system, the upper level of which is involved in a mutual perturbation with the c³Π_u, v = 6 level. The interaction parameters for the perturbation are derived. It is proposed that the appearance of the 6-0 band of the c³Π_u-X¹Σ_g⁺ transition is due to intensity borrowing from the strong, allowed C¹Σ_u⁺-X¹Σ_g⁺ system. Accurate values for the energies of the c³Π_u, b³Π_g, and a³Σ_u⁺ states relative to the ground state are given. The analysis of two other bands, 2-0 and 7-0, of the C¹Σ_u⁺-X¹Σ_g⁺ system whose upper levels likewise interact strongly with the c³Π_u state are also given.     

Low-lying electronic states of BeH+ with the effect of inner electrons

The potential energy curves of the low-lying electronic states of BeH⁺ molecular ion are performed by using highly accurate multi-reference configuration interaction with AV5Z basis sets for H atom and ACV5Z basis set for Be atom, 1s inner shell of Be is considered as the core orbit and the active orbit, respectively, which are used to characterise the spectroscopic properties of a manifold of singlet and triplet states. Fourteen electronic states correlated with eight dissociation channels are investigated, we have found that the a³Σ⁺ and c³Σ⁺ both are bound states, the 3³Σ⁺ possesses double wells, and the C¹Σ⁺, 3³Σ⁺, 2³Π, 2¹Π, 1¹Δ, 1³Δ, 2³Δ and 2¹Δ states are studied for the first time. Transition dipole moment, Franck–Condon factors q_υ′υ^″ and Einstein coefficients A_υ′υ^″ for A¹Σ⁺–X¹Σ⁺, 2¹Π–B¹Π, c³Σ⁺–a³Σ⁺ and b³Π–a³Σ⁺ systems have been calculated. Radiative lifetime of A¹Σ⁺–X¹Σ⁺ band system has also been determined.     

Rotational and vibrational temperatures of electronically excited BiN radicals in a chemiluminescent flame

Rotational and vibrational temperatures of electronically excited BiN radicals in a low-pressure Bi_x+N/N₂*/N₂+Ar chemiluminescent flame have been deduced from high-resolution Fourier-transform emission spectra. Bands of three electronic transitions, a³Σ⁺(a₁1)→X¹Σ⁺(X0⁺), b⁵Σ⁺(b₁0⁺)→X¹Σ⁺(X0⁺), and b⁵Σ⁺(b₁0⁺)→a ³Σ⁺(a₁1), were analysed to determine the optical temperatures in the a³Σ⁺(a₁1) and b⁵Σ⁺(b₁0⁺) states. The rotational temperatures characterising the rotational populations in the a₁1, v=0 and 1 states were determined from the a₁→X, 0-2, 0-3, 0-4, 1-1, and 1-2 bands. The b₁→X, 0-8 and 0-11 bands, and the b₁→a₁, 0-0 bands served to determine the rotational temperature of the radicals in the b₁0⁺, v=0 state. The temperatures derived from the various bands and transitions were well consistent and the mean rotational temperature was determined to be 353±18 K, which is close to the translational temperature of the gas.Vibrational temperatures of the radicals in the a₁1 and b₁0⁺ states were derived from band intensities of the a₁→X and from the b₁→X as well as b₁→a₁ systems, respectively. The Franck-Condon factors needed were calculated with RKR potentials deduced from literature values of the rotational and vibrational constants in the three states involved. The a₁1 vibrational temperature (336±21 K) was close to the rotational temperature, while the b₁0⁺ vibrational temperature (438±36 K) differed, likely due to the previously observed perturbation of the b₁0⁺ state.