溴分子[^2Π3／2]4d里德堡态的转动谱的计算模拟

对溴分子在６８８００－７２００ｃｍ＾－１范围内的两个被观察到的［＾２Π３／２］４ｄ偶宇称里堡态的转动光谱进行了计算模拟，确定了转动常数，并且证实了原先对实验光谱的传动结构和电子角动量的标识。     

332—362nm范围内CF2Cl自由基的共振增强多光子电离研究

用CF₂Cl₂分子直流脉冲放电的方法产生CF₂Cl自由基，结合共振增强多光子电离(REMPI)技术，测量了332—362nm波长范围内CF₂Cl自由基的(2+1)REMPI光谱，分析并标识了4s Rydberg态带源位于(ν_0—0=55371cm^-1)，两个被激活振动模ω′₃(CF₂剪式振动模)和ω₄′(OPL 关键词：     

钠分子^1Пg里德堡态光谱研究

通过光学－光学以共振（ＯＯＤＲ）光谱方法,研究了钠分子六个高激发＾１Пｇ态,对它们进行了振动和转动归属,获得了分子常数和势能曲线。根据里德堡轨道的ｎｌλ特性,将１－１０＾１Пｇ态划分为实贯穿里德堡态和实非贯穿里堡态。     

What is so mysterious about the electronic states of SCI?

The 15 lowest lying doublet electronic states of the molecule SCI have been investigated theoretically at a high level of correlation treatment (MRCI). For the ground state (X ²II), spectroscopic constants were obtained from a set of eight vibrational intervals. This result extends our knowledge about this state beyond the experimentally known data that presently were derived from only two bands. Spin-orbit constants, transition probabilities and radiative lifetimes complement its spectroscopic characterization. For the excited electronic states, a global view of the doublet states is presented that can help us understand the scarcity of experimental data on electronic transitions for this system and also the difficulty of assigning the only two transitions so far recorded. Most of these states are repulsive, and for the few high lying bound ones, of Rydberg character, avoided crossings restrict the number of accessible vibrational states. Crossing by repulsive states and predissociation is also a factor that can prevent further emissions. Two new bound excited states, ²δ and ²Σ, predicted in this study, are of direct relevance to an interpretation of the limited experimental data available on electronic transitions.     

Photo-Absorption Studies on Formaldehyde Using Synchrotron Radiation at Indus I

Photo-absorption spectra of formaldehyde (HCHO) is recorded in the range of 6–11.5 eV at various pressures (<0.001–2 mbar) at an average resolution of 1.2 Å using Photophysics beam line at the 450 MeV Indus-1 synchrotron radiation facilities at RRCAT Indore, India. The spectrum is found to consist exclusively of n → Rydberg transitions converging to the ground state of HCHO⁺. The highest identified Rydberg states, observed up to the first ionization limit of HCHO, correspond to 7s, 11p, 9d, and 12f orbitals. Analyzed electronic spectrum along with the intensities and quantum defects are presented. To interpret the observed weak valence transitions instead of strong valence transitions, a theoretical study of Rydberg and valence electronic states of HCHO is performed in the framework of single configuration interaction (CIS) and time-dependent density functional theory (TDDFT) using different basis sets. Electronic transition energies of high-lying singlet and triplet valence states as calculated using TDDFT (B3LYP) level of theory are found to give fairly-good agreement with the experimental data.     

Theoretical electronic structure and perturbations in SiS

Wavefunctions, SCF-CI energies, and spectroscopic constants of low-lying electronic states of SiS have been computed. Ab initio calculations of parameters characteristic of the perturbations occurring between the valence states of SiS have been performed. The results present, as in SiO, a large difference between ³Π and ¹Π perturbation parameters. Predictions of the magnitude of the corresponding perturbations in heavier molecules (SiSe, SiTe) are reported.     

双光子激发NO分子里德伯态H~(''''2)Ⅱ~-的光谱研究

本文采用激光双光子激发的方法对NO分子的里德伯态H~(12)Ⅱ-(v=1,2)进行了研究,得到了该能级的光谱常数;观测到了H~(12)Ⅱ-与非里德伯态B~2Ⅱ之间的相互作用现象,并计算出了相应的转动能级位移;研究了H~(12)Ⅱ-能级的主要荧光跃迁通道。     

Fundamental constants and tests of theory in Rydberg states of hydrogenlike ions

A comparison of precision frequency measurements to quantum electrodynamics (QED) predictions for Rydberg states of hydrogenlike ions can yield information on values of fundamental constants and test theory. With the results of a calculation of a key QED contribution reported here, the uncertainty in the theory of the energy levels is reduced to a level where such a comparison can yield an improved value of the Rydberg constant.     

Study of Rydberg transitions in NaHe

Einstein coefficients and oscillator strengths for electronic transitions in the Rydberg radical NaHe have been calculated with the molecular-adapted quantum defect orbital (MQDO) method. The correctness of our estimations has been established on the basis of their good agreement with the results of a reliable complex calculation available in the literature. Transition probability data involving Rydberg states lying higher in energy than those so far reported are supplied.     

Photoelectron and electronic absorption spectra of SCl2, S2Cl2, S2Br2 and (CH3)2S2

Photoelectron and electronic absorption spectra of SCl₂, S₂Cl₂, S₂Br₂, and (CH₃)₂S₂ have been measured and analyzed. Quantum chemical calculations (CNDO/ 2 and MWH (Mulliken-Wolfsberg-Helmholtz) have been carried out and the electronic structures have been described in terms of molecular orbital theory. The variation in differential photoionization cross-section as a function of incident photon energy and results of MO computations are used to identify ionization bands and assign ground state MO configurations. Suggested ground state electronic structures coupled with computed virtual MO's are used to interpret the visible and near-ultraviolet electronic absorption spectra. The low energy excited states are described as molecular states followed by the initial members of Rydberg series. Calculated oscillator strengths for molecular transitions are in good agreement with those observed experimentally. Quantum defects, δ, for the Rydberg states have been calculated from the Rydberg equation using the adiabatic first ionization potential.     

The spectrum of Si18O in the vacuum ultraviolet region

The absorption spectrum of Si¹⁸O has been photographed at high resolution in the region 1200–1500 Å. Nine of the recently reported eleven excited states found in this region from a study of Si¹⁶O have been verified and their v numbering settled. From the Rydberg states a value of the ionization potential has been derived.     

Two-color photoionization and photoelectron studies by combining infrared and vacuum ultraviolet

Recent developments of two-color infrared (IR)-vacuum ultraviolet (VUV) and VUV-IR photoionization and photoelectron detection schemes for spectroscopic studies are described. By preparing molecules in selected rovibrational states by IR excitation prior to VUV-photoionization, state-selected and state-to-state photoionization cross sections can be obtained by IR-VUV-photoionization efficiency (IR-VUV-PIE) and IR-VUV-pulsed field ionization-photoelectron (IR-VUV-PFI-PE) measurements, respectively. Rotationally resolved autoionizing Rydberg states converging to excited ionic states, which cannot be observed by single-photon VUV-PIE measurements, can be examined by the IR-VUV-PIE scheme. By monitoring the photoion and the PFI-PE intensities at a fixed VUV energy as a function of IR frequency, the respective IR photoion and IR absorption spectra of the corresponding neutral molecule can be measured. Two-color VUV-IR photo-induced Rydberg ionization (PIRI) experiment, in which high-n Rydberg states are prepared by VUV-photoexcitation followed by IR-induced autoionization, has also been demonstrated. Since the IR-VUV-PIE, IR-VUV-PFI-PE, and VUV-IR-PIRI methods do not require the existence of a bound intermediate electronic state in the UV and are generally applicable to all molecules, the development of these two-color photoionization and photoelectron schemes is expected to significantly enhance the scope of VUV spectroscopy and chemistry.     

Rydberg states of the PO molecule

The absorption spectrum of the PO molecule in the region 2100 to 1550 Å has been studied in detail at high resolution. From a rotational analysis of the spectrum, a number of new electronic states have been discovered. Some of these electronic states have been assigned to Rydberg series of the various nl complexes of PO. An upper limit of the ground state dissociation energy has been lowered to 49090 cm^?1 (X²Π, T₀ = 0). Quantum defects are calculated and the first ionization potential of PO is improved to 67 532 cm^?1.     

A comparative study of RKRV and reduced potential curves of the ground states of alkaline-earths chlorides

In light of the recording and analyzing of high resolution FT spectrum of MgCl molecule, a comparative study of the RKRV and RP curves of the ground states of alkaline earth chloride viz. BeCl, MgCl, CaCl, SrCl and BaCl have been made using latest molecular constants. The H-H and extended Rydberg potential functions compete each other and have excellent agreement with RKRV curves for all the molecules. Because of the use of improved constants the Potential Energy curves in present study are better as compared to earlier workers.     

N-乙基吡咯S1态超快动力学：飞秒时间分辨光电子成像研究

N-乙基吡咯是吡咯分子的一个乙基取代衍生物,它的激发态衰变动力学目前为止很少被研究. 本文利用飞秒时间分辨光电子成像的实验方法研究N-乙基吡咯分子S₁态的衰变动力学. 实验采用241.9和237.7 nm的泵浦激发波长. 在241.9 nm激发下,得到5.0±0.7 ps,66.4±15.6 ps和1.3±0.1 ns三个寿命常数. 在237.7 nm激发下,得到2.1±0.1 ps和13.1±1.2 ps两个寿命常数. 所有寿命常数都归属为S₁态的振动态. 本文并对不同S₁振动态的弛豫机理进行了讨论.     

Non-empirical CI potential curves for the ground and excited states of PH and its positive ion

A series of calculated potential curves is reported for the low lying valence and (selected) Rydberg states of the PH molecule by employing the multi-reference (single- and) double-excitation CI method. A large AO basis including f functions on phosphorous is chosen for this study and up to twenty main configurations are used to generate a given MRD-CI space in the accompanying theoretical treatment. Very good agreement is obtained between calculation and experiment for a variety of spectroscopic constants and a number of predictions for electronically excited states of PH are made for cases in which no comparable empirical data are yet available. The repulsive ⁵∑^- state is shown to be responsible for the predissociation of several states of the neutral system and is also thought to explain the failure to detect a number of low lying Rydberg states experimentally. Analogous calculations for the PH⁺ molecular ion have also been carried out and spectroscopic constants for this system are reported. In this case the ⁴Π state plays much the same role as the neutral ⁵∑^- species in bringing about predissociation in its electronic spectrum. Finally a comparison is made throughout between the results for PH and PH⁺ and a number of isovalent systems, especially NH and NH⁺ and also SiH.     

Pressure induced configuration demixing in the electronic spectrum of NO

Previous low resolution studies indicated that, in the absorption spectrum, transitions to Rydberg states are far more sensitive to pressure than transitions to valence states in accordance with the complete vanishing of Rydberg bands and the deperturbation of the valence bands in the spectrum of NO trapped in a solid rare gas matrix. The present study of NO is the first extensive investigation of medium and high resolution molecular electronic spectra subjected to pressure of foreign gases. It is observed that, at the highest pressure attained (～1000 bar), almost all of the Rydberg bands have vanished whereas the remaining valence bands stay relatively sharp. While high pressure medium resolution spectra give information about the deperturbation of intensities and of vibrational spacings of the valence bands, inspection of low pressure high resolution spectra reveals that the rotational lines react to pressure in a way reflecting closely the degree of configuration mixing between Rydberg and valence states.     

分子里德伯态的电子能级结构——一些小分子及分子离子的里德伯能级结构

本文在独立电子近似的基础上,利用多重散射自洽场理论方法,计算了He₂,H₂等分子和He₂⁺分子离子的里德伯能级结构。根据分子的电子组态极限,确定了各里德伯系列初始态的主量子数,阐明了这些分子和分子离子里德伯能级结构的变化规律。理论计算的结果同已有的实验数据符合良好,从而为超越独立电子近似的计算打下了基础。