Excitation of the K2 molecule by the 406.7 nm and 413.1 nm Kr+ laser lines

Summary Two blue lines (406.7 nm and 413.1 nm) of a Kr⁺ laser have been used to excite the potassium dimer K₂. We have analysed the spectral region between 400 nm and 800 nm where a rich fluorescence spectrum has been observed as the result of different decay processes. Some of these features have not been reported previously; in particular we interpret the blue fluorescence (≈(400÷470) nm) as due to theC→X andD→X bands, as indicated also by the absorption spectra recorded in this region for different temperatures.

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Riassunto La molecola biatomica di potassio K₂ è stata eccitata con due righe blu di un laser a Kr⁺ a 406.7 nm e 413.1 nm. A causa di molteplici processi di diseccitazione è stato osservato un ricco spettro di fluorescenza che copre quasi tutta la regione spettrale analizzata in questo lavoro tra 400 nm e 800 nm. Alcune parti dello spettro non erano state riportate in precedenza; in particolare, interpretiamo la fluorescenza nel blu (≈(400÷470) nm) come dovuta alle bandeC→X eD→X, come indicato anche dagli spettri di assorbimento ottenuti in questa regione spettrale per diverse temperature.

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Резюме Для возбуждения двух-атомной молекулы K₂ используются две голубые линии (406.7 нм и 413.1 нм) Kr⁺ лазера. Мы анализируем спектральную область между 400 нм и 800 нм, где наблюдается богатый спектр флуоресценции, который является результатом различных процессов распада. Некоторые хварактеристики спектра ранее не наблюдались; в частности, мы интерпретируем голбую флуоресценцию (≈(400÷470) нм), как обусловленную зонамиC→X иD→X, что также подтверждается спектрами поглощения, которые были зарегистрированы в этой облавсти для различных температур.

     

Identification of a forbidden ammonia transition: Confirmation by pressure broadening measurements

Summary Pressure broadening measurements confirm the identification of the forbidden ammonia transitionss ⁻³(4, 3) at 887.780 cm⁻¹, Moreover, its pressure shift together with those of submillimeter transitions adds new confidence on the validity of the shift additivity.

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Riassunto Misure di allargamento per pressione confermano l'identificazione della riga proibita dell'ammoniacass ⁻³ P(4,3) a 887.780 cm⁻¹. Inoltre il suo spostamento per pressione insieme agli spostamenti di transizioni submillimetriche dimostra ancora una volta la validitá dell'additività negli spostamenti.

     

Determination of the cubic force field of nitrosyl fluoride by vibration-rotation α constants and sextic centrifugal distortion constants

Summary The rotational spectra of ONF in the (100), (010) and (001) excited vibrational states were observed and the corresponding vibrationratation α constants determined. A centrifugal-distortion analysis of 156 ground-state rotational transitions yielded accurate values of all the sextic centrifugal-distortion constants. Both vibration-rotation α constants and sextic centrifugal-distortion constants were used to determine, by least-squares methods, the cubic part of the general valence force field of nitrosyl fluoride. Anab initio calculation provided reliable constraints for the three cubic terms of the potential-energy function which are not directly determinable by the available experimental data. Supporting organizations: C.N.R. and M.P.I.     

14N and35Cl nuclear quadrupole coupling constants in thiazyl chloride from microwave spectroscopy andab initio molecular orbital computations

Summary The¹⁴N and³⁵Cl nuclear quadrupole coupling constants of the¹⁴N³²S³⁵Cl isotopic species of thiazyl chloride have been determined from an analysis of the hyperfine structure of sixμ _a andμ _b transitions in the microwave spectrum as (in MHz) _χaa (³⁵CL) = −39.00(3), _χbb (³⁵CL) = 23.84(4), _χaa (¹⁴N) = −1.42(6), _χbb (¹⁴N) = −4.16(6).

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Riassunto Le costanti di accoppiamento quadrupolare di¹⁴N e³⁵Cl della specie isotopica¹⁴N³²S³⁵Cl del tiazil cloruro sono state determinate attraverso l'analisi della struttura iperfine di sei transizioni di tipoμ _a eμ _b dello spettro a microonde. Si sono ottenuti i seguenti valori (in MHz): _χaa (³⁵CL) = −39.00(3), _χbb (³⁵CL) = 23.84(4), _χaa (¹⁴N) = −1.42(6), _χbb (¹⁴N) = −4.16(6).

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Резюме Из анализа сверхтонкой структуры шестиμ _a иμ _b переходов в микроволновом спектре определяются ядерные квадрупольные константы связи¹⁴N и³⁵Cl в¹⁴N³²S³⁵Cl. Получены следующие значения (в МГц): _χaa (³⁵CL) = −39.00(3), _χbb (³⁵CL) = 23.84(4), _χaa (¹⁴N) = −1.42(6), _χbb (¹⁴N) = −4.16(6).kg]PACS. 33.20

     

Optogalvanic detection of negative ions in discharges

With the aid of rf, microwave and dc discharges, an optogalvanic (OG) signal, due to the photodetachment of negative oxygen ions, has been observed. The OG signal intensity in an rf discharge was successfully estimated from the discharge parameters. Thus, the OG technique may be potentially useful as a plasma diagnostic method. Furthermore, the OG signal from negative oxygen ions is found to be strong in the diffusion-controlled positive column, while the OG signal due to the excited levels of atomic oxygen is strong in the cathode fall region. Preliminary results for the observation of the OG signal in discharges of H₂, CO, H₂O₂, and (COCH₃)₂ are also described.     

Optogalvanic detection of 7s-nP transitions in cesium

Using a single frequency ring laser with styryl-9 in the wavelength region 790 to 890 nm, optogalvanic signals of the 7s-nP transitions have been observed with excellent signal-to-noise ratio, making a frequency stabilization to one of these atomic transitions possible.     

Deep-UV high resolution cavity ring-down spectroscopy of the Schumann-Runge bands in O2 and O2 at wavelengths 197-203 nm

With the use of a novel titanium:sapphire laser source delivering, upon fourth harmonic generation, narrowband and tunable radiation in the deep-UV, spectroscopic studies were performed on weak Schumann-Runge bands of oxygen. Improved values for rotational and fine structure molecular parameters for the , v = 0-2 states of ¹⁶O₂ were determined, as well as values for the v = 0-1 states in ¹⁸O₂. Signal detection was accomplished via cavity ring-down spectroscopy.     

New band system of YbI molecule

Thermal emission spectrum of YbI molecule has been photographed for the first time in the spectral regionλλ 6100–6400 Å using Saha’s high temperature furnace at a reciprocal linear dispersion of 7.3 Å/mm. A total of 52 single-headed and violet degraded bands have been recorded and are classified into a single system. Vibrational analysis has been carried out and it has been suggested that system arises from the ground state with the vibrational constantω″ _e=153.0 cm^?1.     

High-resolution laser spectroscopy of the potassium-argon molecule: The BΣ state

The absorption spectrum of the KAr molecule has been observed with high resolution between 13 032 and 13 077 cm⁻¹ using tunable laser diodes as light sources, a supersonic beam for production of the molecules, and laser-induced fluorescence for detection. In addition, optical-optical double resonance (OODR) experiments have been performed to simplify the spectrum and to get rotational assignment. Altogether, 670 lines due to the transition B²Σ⁺ ← X²Σ⁺ have successfully been assigned with vibrational levels of the B state ranging from v = 0 to v = 6. The corresponding energy values were fitted to the well-known Dunham expansion. In addition, we were able to analyse a local perturbation between the vibrational level v = 1 of the B state and v = 14 of the A²Π_3/2 state. Unexpected extra lines in the OODR spectra are most probably due to a collision-induced population of other levels. For the equilibrium distance and the well-depth of the B state we obtain from the Dunham expansion 7.03 (8) Å and 26.2 (8) cm⁻¹, respectively.     

Optogalvanic detection of velocity-selective optical pumping in an open, cascade atomic medium

We performed two-color spectroscopy of the (4s²) ¹S₀ → (4s4p) ¹P₁ → (4p²) ¹D₂ calcium atomic transition and observed velocity-selective optical pumping in a calcium hollow cathode lamp by means of optogalvanic detection. The optical pumping signature in optogalvanic detection is compared to that of fluorescence and transmission detections. The optogalvanic technique is found to be a very sensitive method of detecting optical pumping and could be used in distinguishing optical pumping from electromagnetically induced transparency.     

New band system of MnSe molecule

Thermal emission spectrum of MnSe molecule, excited in high temperature graphite furnace, has been photographed in the spectral region λλ4150–5800 Å at a reciprocal linear dispersion of 7.3 Å/mm. The study reveals the presence of two band systems viz.A–X andB–X in whichB–X is entirely new. While the systemA–X consists of 29 bands, the new systemB–X comprises of 24 single headed and red degraded bands. Vibrational analysis performed suggested that both the systems involve ground state⁶Σ with a vibrational frequencyω″ _e =361.0 cm^?1. Transition responsible for MnSe spectrum appears to be of the type⁶Σ–⁶Σ. An estimation of the ground state vibrational frequency for MnTe molecule gives rise to its value as 280 cm^?1.     

Laser-induced breakdown spectra of Zn2 molecule in the violet region

Laser-induced breakdown spectrum has been recorded in the region of 380–455 nm using second harmonics of Nd:YAG laser, computer-controlled TRIAX 320 M monochromator with a reciprocal linear dispersion 2.64 nm/mm fitted with ICCD detector. The spectrum consists of 108 bands, which are classified into four new subsystems E0 _u ⁺ (¹Σ _u ⁺ ) → A1_g(³Π_g), J0 _g ^± \1_g(³Σ _g ⁺ ) → D1_u(¹Π_u), F1_u → A0 _g ^± (³Π_g) and F1_u → A2_g(³Π_g) along with additional bands of the known system E0 _u ⁺ (¹Σ _u ⁺ ) → A0 _g ^± (³Π_g). The molecular constants for these systems have also been determined.     

电场对分子线电子结构的影响

从第一性原理出发,利用密度泛函理论计算了分子2-氨基-5-硝基-1,4-二乙炔基-4-苯硫醇基苯与金原子团形成的分子线的电子结构,从轨道、能级及吸附电子三个方面讨论了电场对分子线电子结构的影响.该工作将有利于未来纳米电子学器件的设计.     

Optogalvanic Diagnostic of Conical Bottom Hollow Calhode Discharge. Enhancement of the Optogalvanic Signal

We present an optogalvanic aspect of a new modification of Hollow Cathode Discharge (HCD), i.e. conical bottom HCD. Earlier we found this modification enhancing the light emission properties of the conventional flat bottom HCD; a greater concentration of sputtered atoms was established by using a level crossing method. This effect provoked us to investigate the conical bottom HCD as an optogalvanic detector of signals, belonging to the sputtered atoms in the negative glow. The conical bottom HCD is found to be an effective optogalvanic detector due to the structure of the radial distribution of the optogalvanic signal.     

New band systems of NiBr molecule in visible region

Thermal emission spectrum of NiBr molecule excited by vacuum graphite tube furnace revealed the existence of ten new band sub-systems in the region λλ 5540-4720 Å which were attributed toA→X,B→X,C→X andD→X transitions. Vibrational analysis was carried out for each of the systems mentioned above.A ² Δ has been suggested as the ground state of NiBr molecule with an electronic interval of about 533 cm^?1. Transitions responsible for NiBr spectrum appear to be of the type²π–²Δ and²Δ–²Δ.     

高分辨分子吸收光谱中的波长校准方法

本文提出高分辨分子吸收光谱中，以碘分子谱作为参考标准的波长校准方法，编制了以人机交互方式自动完成波长校准的软件，并应用于16 422-17 896cm^-1可见光波段范围内的N2^ 分子离子的高分辨吸收谱线的波长校准，结果表明其绝对准确度可达0.006cm^-1。     

低压段DHPM作用对木瓜蛋白酶结构影响的荧光光谱分析

以荧光光谱为检测手段研究了低压段(60～100 MPa)动态高压微射流作用(DHPM)对木瓜蛋白酶(Papain)分子结构的影响。结果显示,在60～100 MPa下经DHPM处理后,Papain,Tyr残基和Trp残基荧光强度均有不同程度降低,且随着处理压力的增加,Papain,Tyr残基和Trp残基的荧光强度逐渐增大,Papain,Trp残基荧光发射峰的位置分别从未处理时的334和277.5 nm逐渐红移至100 MPa处理后的335和278.5 nm;在0～4 ℃放置24 h后,Papain,Tyr残基和Trp残基的荧光光谱均基本保持了0 h时的变化趋势。表明低压DHPM处理后,Papain中Trp残基逐渐暴露出来,并形成了较为稳定的新分子构象。     

乙二醇和丙三醇的吸收光谱和荧光光谱研究

对乙二醇和丙三醇的紫外吸收光谱和荧光光谱进行了实验研究和理论分析,发现两者的最大吸收波长均位于198 nm,且在适当的紫外波长激励下均能发射出荧光,文章中给出了相应的荧光光谱图,但荧光相对强度和激发波长间似乎没有明显变化规律,其原因有待进一步探索。从乙二醇的一阶导数荧光光谱,得知在210 nm激发下荧光相对强度随时间变化最快,在225 nm激发下的绝大多数时间内变化速率最慢。另外,文章还从量子计算出发,采用一维势阱模型,根据电子从HOMO到LUMO的跃迁,计算出了两者的吸收波长值。比较分析了计算值与实验值之间的误差,考虑到将分子直链化后其键长与实际情况有所差别,结果认为理论计算有一定的参考价值。     

傅里叶变换红外光谱测量热气体温度新方法初步研究

详细地讨论了分子转振光谱理论,总结了影响分子转振光谱结构和强度分布的因素,得知各谱线相对光谱强度(即归一化光谱)只与温度有关,其分布结构与温度一一对应。根据这种特性,文章提出了一种利用傅里叶变换红外光谱测量热气体温度的新方法。从HITRAN标准数据库中提取数据建立了一个测温数据库,并用4个不同温度的实测光谱数据对建立的测温数据库进行定标和检验。用定标后的测温数据库所得的测量温度与实测温度吻合得非常好。与目前常用的两种遥感测温方法(分子发射基带最大强度光谱测温法,分子转振光谱测温法)相比,该方法的优点是：物理过程简单,容易计算,精度高,是一种简单实用的方法。